There are few ambient electronic artists as consistent and groundbreaking as Tim Hecker, even if the terms “ambient” and “electronic” barely encompass the scope of his work. He does use electronic manipulation to create drone-infused atmospheres, but in recent years, he has increasingly relied on live recordings of orchestral elements to form a base for that work. Meanwhile, the fundamental characteristic of “ambient” music – generally pegged as background drivel by its very definition – seems a complete misnomer, as Hecker’s work demands to be heard under the same kind of meditative hyper-focus with which he makes it.

For 15 years now, Hecker has chased down particular moods and even physical sensations with a batch of records that have garnered increasing recognition. He began his career releasing minimal electro under the moniker Jetone, but abandoned the project early on, finding its reliance on club beats too restrictive. With a PhD in sound studies from McGill, Hecker started producing eponymous work that disrupted musical experience, both explicitly and subtly. The way he layered instrumental elements over billowing white-noise collage (both within individual tracks but also across entire albums) made drone and ambient fans take note from the get-go, inspiring a fervent devotion in the early aughts, while the rest of the world was listening very earnestly to indie rock. Fast forward to today: Love Streams, his eighth full-length solo album and first for 4AD, and Hecker has become a known entity outside the insular scene he came up with.

Most of Hecker’s records provide the listener with a continuous auditory experience; there are individual tracks, but they often bleed together to form a cogent whole. In an era of Spotify playlists and Hype Machine trends that favor hot-take singles over full-album playback, Hecker has staunchly favored the latter. If you’ve got a spare 10 hours (give or take), it is possible to begin with 2001 debut Haunt Me, Haunt Me Do It Again and end with Love Streams, which was released this month, as one long opera, a diary of thoughts and concepts painstakingly explored by an unassuming composer in his Montreal studio. The chronological playback is surprisingly, satisfyingly connected.

So why rearrange Hecker’s works from worst to best, especially when there isn’t much to fault on any of these releases? For one thing, recognition for Hecker’s work has steadily increased, and though his most recent albums are some of his strongest, it can be useful to reevaluate what came before. These albums engage listeners on multiple levels – the conceptual, the sonic, and even the physical – and there are clear standouts if attention is given to Hecker’s purpose as an investigator of musical stimuli, rather than just a tape manipulator. He is a scientist as much as he is a musician, and his music uncovers a persistent phenomenon in a way that is so specific it cannot be accidental.

This phenomenon, known to those who experience it as Autonomous Sensory Meridian Response, or ASMR, didn’t have a name when Hecker began composing, but awareness of it has increased so dramatically that there are now numerous online communities dedicated to it, as well as a slew of YouTube channels featuring videos meant to trigger it. Not only does Hecker’s music prominently feature elements that do so, the very sound of it mimics aspects of the ASMR experience, said to be analogous to euphoria, characterized by a tingling sensation that moves along the skin from the scalp down the spine. It’s been described as static-like, as an electrical current, as carbonation. In reviews of Hecker’s work, alongside the recognition that you can feel this music as much as you can hear it, the words “static” and “electricity” come up again and again. A holistic reckoning of Hecker’s catalogue renders his output as a unique sort of therapy: drone with a purpose that goes beyond what others operating within the genre typically apply.

If you can see through the fog and darkness at a Tim Hecker show, you won’t spy heads bobbing or hips gyrating. You see a blissed-out crowd feeling the low-end throb through the venue’s beams and floorboards. No one is waiting for a drop. They’re listening (hopefully through earplugs, because Hecker gigs are notoriously loud) for the specter of some haunted melody drifting up through the pulsating static, feeling it in every vertebra. On headphones or an audiophile’s home speaker system, that experience comes through in Hecker’s recorded output, too. He is more beholden to his pursuits than most artists (in his genre, or in any other), and that integrity has begun to have a big payoff.

For those who might feel overwhelmed in the face of it, this list may serve as a guideline for where to start in on Hecker’s catalogue. I didn’t include Jetone releases (as those have an entirely different feel) or eponymous EPs (since some are sketches for other records, while others, such as Norberg or Atlas, are long, single tracks that would be difficult to evaluate using the same criteria as full-lengths). I did, however, include two collaborations Hecker made with Aidan Baker and Daniel Lopatin in 2008 and 2012, respectively. These were made during gaps in Hecker’s solo discography; I felt their inclusion was important because it showcases his adaptability in working with others, while also highlighting his distinct imprint against like-minded artists.

10. Instrumental Tourist with Daniel Lopatin (Oneohtrix Point Never) (2012)

By 2012, Hecker was renowned as a visionary in electronic music circles, and part of an insular community of noise musicians dabbling in glitchy, deconstructed soundscapes. While Hecker had already been at his craft for a decade, relative newcomer Daniel Lopatin (otherwise known as Oneohtrix Point Never) was a recent star, having been involved in numerous collaborative projects before releasing his first solo work in 2007, populated with sci-fi and New Age samples. By 2010 Lopatin had founded his own record label, Software. Intended as a launch for the Software Studios Series (collaborative albums released via Lopatin’s imprint) Lopatin poached Hecker for a fully improvised session – not via emailed sound files, but recorded while the two were in the very same room.

On the one hand, Lopatin and Hecker made for obvious bedfellows, both exploring themes of obsolescence and decay in their solo efforts. Neither were very much accustomed to spontaneous, off-the-cuff composing, and while a sense of playful looseness does come through, it’s doesn’t necessarily trump the controlled processes of manipulation more characteristic of both artists’ output. With no sense of purpose, and Lopatin lacking the kind of restraint that Hecker is known for (almost to a fault), there are too many awkward interjections that veer into pastiche (“Racist Drone,” or the album’s title track for instance) or feel intentionally abrasive (“Scene From A French Zoo,” “Intrusions”).

Instrumental Tourist is interesting in the way that Dropped Pianos is interesting – on that 2011 EP, Hecker revealed the sketches for the music that would become opus Ravedeath, 1972 – in that it provides a window into the experimental processes at work. As such, devotees of either Hecker or Lopatin may get a kick out of it, but it’s not a great entry point into Hecker’s work alone, and that has a lot to do with Lopatin’s style taking precedence. Hecker’s earlier collab with Aidan Baker was far more successful, because both Baker and Hecker give nuance the same value, whereas Lopatin dispenses with nuance altogether. The release might have had potential as a starting off point for further manipulations, and though there’s some value in the as-is presentation, in the end, Instrumental Tourist feels as tacky as the floral shirts, khaki cargos, and selfie sticks of a guest that’s overstayed their welcome.

9. Mirages (2004)

After breaking serious ground with his first two albums, Hecker’s inspiration and focus tapered off for 2004’s Mirages. It came at a time when both discourse about electronic music and the technology used to make it needed to catch up to Hecker’s ideas, and the gap between the two is at least partially responsible for the soupiness of this record. His previous works were praised for their seamless continuity, and Mirages feels like a stubborn reaction to that, a resistance to being pegged as a composer of heady, endless movements. The first five tracks alternate at opposite ends of Hecker’s spectrum: the pained screech of opener “Acéphale” crumbles into the lull of “Neither More Nor Less,” which ends in the muted, soothing voice of a phone-sex line operator offering touch-tone options for stimulation. Hecker presses “2” for Domination and Submission, fading the track into the punishing squall of “Aerial Silver.”

By the time things settle midway through the album, it’s hard to get a grasp on what else Hecker’s trying to accomplish; Mirages never feels as unified or developed as his other records. He mostly seems intent on reminding us how enamored he is of shoegaze and metal (see 2002 EP My Love Is Rotten To The Core, entirely built on Van Halen samples) and he relies on guitar distortion far too much, inviting collaborators Oren Ambarchi (“Kaito”) and David Bryant (“Incurably Optimistic!”) to lend some guitar feedback. But that’s over-saturated, sticky territory, populated by the likes of Aidan Baker (whom he would later collaborate with on the far stronger Fantasma Parastasie), Kevin Shields, Sunn O)))’s Stephen O’Malley, Rhys Chatham, and countless others, and at this point, Hecker’s piano manipulations already had more personality.

All that being said, like any Hecker record, there are transcendent moments on Mirages, even if overall, its potential seems mishandled. There’s the fuzzy, stoic swirl of “Aerial Light-Pollution Orange;” “Kaito,” with its steady, then staccato, drips and pops; the low, gutturally satisfying rumble of “Balkanize-You;” the submerged quality of “Counter Attack.” And then there’s the album’s nearly 11-minute closer, “Incurably Optimistic!” which, though perhaps ironically named, does offer a respite from the heavy slog of the preceding material. Hecker gives this track proper time to build and relax, and its soothing presence is the main payoff.

8. An Imaginary Country (2009)

Nestled in the body of his other work, An Imaginary Country seems to bear out the more traditional role of so-called “ambient” music – mainly as background noise – than the boundary-pushing efforts Hecker made prior to its 2009 release. That is to say, unlike the rest of his catalogue, it can be too easily tuned out, never demanding the sort of attention his other releases do. To be fair, Imaginary was the follow-up to his most beloved work to that point, Harmony In Ultraviolet, and it falls victim to the same sort of humdrum routine Hecker found himself repeating on Mirages – these records represent the valleys that come after his most creative peaks. But whereas Mirages can be abrasive, Imaginary is stunningly beautiful, if a bit saccharine. It’s exploratory, both in terms of Hecker’s sonic goals, and in terms of its prevailing theme, in which Hecker marks out the boundaries of some luminescent locale that does not physically exist. The desolate cityscapes referenced by his earlier work give way to the lush topography of “The Inner Shore,” the airy lullaby of “A Stop At The Chord Cascades” and the soft percussive washes of “Borderlands.” It’s hard to fault him for making something that’s too pretty, even if his stunning vistas lack teeth and the theme gets handed to listeners on a silver platter.

The only real suggestion of darkness in this drone-topia comes late in the game; we finally get some of that staticky Hecker low-end on “Where Shadows Make Shadows.” Notable too, is the soaring shoegaze shred of “Paragon Point.” But overall, An Imaginary Country paints Hecker as a passive wanderer without a sense of purpose, rather than the authoritative role he usually takes as a master of intense sensory exploitation.

7. Fantasma Parastasie With Aidan Baker (Nadja) (2008)

If a fog machine could be rigged to also play music, Fantasma Parastasie is exactly what it would spit out. The product of a fortuitous collaboration between Hecker and fellow Canadian experimentalist and Alien8 label-mate Aidan Baker, Fantasma feels far more consistent and thought-out than his joint effort with Daniel Lopatin would four years later.

Baker is primarily a guitarist, and that’s felt immediately on this release. As a habitual improviser with nearly a hundred solo releases, plus dozens more via his drone duo Nadja (with wife Leah Buckareff), Baker’s spontaneity and intuition benefitted Hecker greatly, giving him salient building blocks to distort and manipulate. Poking fun at Hecker’s proclivity to mine his interest in the supernatural for thematic material, the content of the record makes reference to a spooky, vintage spiritualism. At only 34 minutes, it’s easily digestible, even if the digital version split the seven tracks into 66 arbitrary snippets rarely more than a full minute long. In an era where the iPod shuffle sought to revolutionize listening, Baker and Hecker evidently wanted to remind listeners that a back-to-front, holistic experience still had a place in music.

Hecker was already (and to some extent, still is) branded something of a loner, a lurker so obsessed with isolation that his music couldn’t help but reflect it. There’s something to be said, then, for the seemingly effortless give-and-take of Hecker as collaborator – for his ability to retain the trademarks of his own work while welcoming the renewal of another’s, each musician playing to his own strengths. From the subtle, echoic sheen he gives Baker’s delicately plucked intro for “Auditory Spirits,” to the sinister layers of density he adds to the distortion of “Skeleton Dance,” each artist’s decisions feel wholly congruent and rooted in true consensus.

6. Haunt Me, Haunt Me Do It Again (2001)

To those acquainted with Hecker via his work under the moniker Jetone, the debut credited to his given name must have seemed bleak and ragged. Though he released Ultramarin as Jetone that same year, there’s virtually no comparing it to Haunt Me, Haunt Me Do It Again; he wasn’t simply using different tools for each project, but creating them within completely separate frameworks. Slavish as Jetone was to club beats, the only foreshadowing of Hecker’s future trajectory is Ultramarin’s fourth track, the tellingly-named “Static.” With Haunt Me, Hecker broke the minimalist mold wide open, quickly establishing the earmarks of his eponymous efforts.

Presented mostly as a collection of flowing song suites, Haunt Me sizzles with that aforementioned static, popping with electricity and seeming to have emerged through a frayed wire cable. The hum on opener “Music For Tundra” links its three movements almost subliminally, morphing into creepy, supernatural whispers by the end of “Part 3.” That disembodied garble comes through again in “October Part 2,” perhaps stemming from an interest in culling electronic voice phenomena out of white noise, a full three years before Ghost Hunters landed on cable to regularly document such spooky occurrences. It was easy to imagine Hecker, not as an electronic composer feeling out new sonic territory safely from a studio in Montreal, but as an icicle-laden Arctic explorer, alone save for frozen apparitions populating the icy magnetic poles, helplessly twisting a radio dial in search of a vague memory of civilization and finding only a faint transmission of Sade on which to settle. His next full-length, Radio Amor, would take that concept to its extreme, replacing the tundra and its attendant spirits with the open sea and the specter of short-wave companionship.

Hints of dub almost surface during the last moments of the twinkling, expansive “Boreal Kiss” suite, but ultimately remain submerged under dense ice. The album’s one stand-alone track, “The Work Of Art In The Age of Cultural Overproduction,” acts as an official kiss-off to his Jetone aspirations, though he would revisit the project in 2006 with Sundown. Feeling bound by the trappings of techno, Hecker was already on a different wavelength with Haunt Me, clearly seeking something that would trigger ASMR-induced enlightenment, and he ran with it.

5. Love Streams (2016)

The critical acclaim garnered from the one-two punch of Ravedeath, 1972 and Virgins garnered Hecker some wider exposure, including attention from major indie label 4AD after he’d toiled for years at smaller imprints Kranky and Alien8. Those labels allowed Hecker a lot of growth and respect, but are still concerned mostly with niche projects; 4AD, by comparison, has a way of taking reputable artists (or in this case, well-established  visionaries) and giving them full breadth (and a full budget) with which to go all out. Hecker’s indulgence, it turns out, was unexpected given his trajectory – on Love Streams, it’s not piano or guitar he meddles with, but the human voice.

In the 15 years since Hecker began his journey, strides in technology have made his most grandiose undertakings achievable. Using a program called Melodyne, which re-scores digital audio for sheet music, he distorted an existing Renaissance-era work by Josquin des Prez, then handed it over to Sicario composer Jóhann Jóhannsson. Jóhannsson wrote the choral arrangements for eight Icelandic singers in “reverse Latin;” Hecker sat in on the recording, attacking it later in ProTools. The cover of Love Streams, his brightest to date, eschews his stark photographic work for a neon X-ray of the choir, and that’s exactly what you hear on the record – simply the bones of that moment. Though the words are certainly unintelligible, the arrangement for “Music Of The Air” seems almost conversational, albeit between the sort of celestial beings that have been blipping in and out of his work since the beginning. “Violet Monumental” is one of the most urgent things he’s ever done, the voices skipping and shouting like a manic asthmatic desperate to catch a breath over a rattle of steel drum.

Both Ravedeath and Virgins made use of live recordings, but those were instrumental ones; by contrast, the instrumentation on Love Streams feels more synthetic than anything else Hecker has put to tape (apart from that chorus, of course). Exceptions appear in the skittering, spidery guitar fragments of “Voice Crack,” but it’s entirely possible that longtime Hecker fans might be off-put but the new-agey elements on tracks like opener “Obsidian Counterpoint,” hinging, as it does on airy flute and synthetic gongs. But closer “Black Phase,” provides some modicum of reliability, its roiling low-end shot through with the heavenly voices that will cement Love Streams one of the most distinctive offerings in Hecker’s oeuvre.

4. Radio Amor (2003)

Less cerebral than Haunt Me, Hecker’s sophomore effort under his own name benefitted from the greater accessibility of its elements – recognizable, almost human voices; the tidal ebb and flow of his buoyant piano snippets. With Haunt Me (and his previous efforts as Jetone) Hecker’s songs felt almost wholly electronic (whether they were or not) but Radio Amor introduced more straightforward musical elements without sacrificing the bold experimentation that marked his debut. Though the piano is immediately recognizable (on “Song Of The Highwire Shrimper”) its notes are distended, rippling, and sometimes buried by oceanic washes of fuzz. On particularly notable stunner “I’m Transmitting Tonight,” the piano cascades gorgeously upon itself, though by “Shipyards Of La Ceiba,” it’s coated in barnacles and salt rime.

More accessible, too, was Hecker’s source material; Radio Amor is said to have been inspired by a trip to a Honduran fishing village, where he met Jimmy, the highwire shrimper immortalized on the LP’s opening tracks. Speaking of which, “(They Call Me) Jimmy” is particularly arresting, with the gong-like beat on its back half, broken by the phase-filtered thrum that soars throughout. It’s a perfect example of Hecker’s evocative use of repetition, morphing slightly as the song progresses.

On its penultimate track, “Azure Azure,” Hecker lets the hull of Radio Amor sink back into the watery depths, getting colder as it descends, the pressure of 6,000 fathoms embodied in its drone. The calm drift of “Trade Winds, White Heat” follows, offering a bit of closure. In the span of just two records, Hecker had established an indelible imprint, so essential in the world of electronic music in terms of standing out against the pack.

3. Virgins (2013)

Though Steve Reich’s influence is certainly felt throughout Hecker’s body of work, 2013 breakout Virgins is arguably his most Reichian, featuring the kind of vaporous builds and incrementally-shifting repetition that characterized the minimal pioneer’s mid-seventies masterpiece Music For 18 Musicians. The clattering, clanging piano line reminds listeners that despite all those strings and keys, the piano is still a percussion instrument; this is not the cascading, tonal tip-toe of Radio Amor, but a jolt of multi-hued piano-born textures, elasticized, layered, and sometimes even tracked in reverse (as on “Prism,” which opens the album with dramatic unease) or looped over a stuttering, breathy pulse (as in the methodical ache of “Black Refraction”).

Like Ravedeath, 1972, the album he released two years prior, Hecker recorded live instruments in Reykjavík, this time with an ensemble. Where that album sought to desiccate the audio and find something breathtaking within the decay, Virgins is a revelatory experience concerned with the investigation of an exquisite kind of tension. Forlorn woodwinds bathed in tape hiss provide a through-line as the piano notes swing like pendulums, only to crash into one another or creak uneasily until they break. On back-to-back tracks “Live Room” and “Live Room Out,” Hecker rends the Reykjavík recording session asunder with harsh rips of static that feel almost physical, then tenderly stitches it back together with a balm of gilded strings and reedy, whispering oboe. Each note feels sacrificial, like the martyrs Hecker used as a guiding theme.

That theme shows a kind of fearlessness in Hecker that had not been previously seen, as he mines the darker aspects of religious experience. The late-album suite “Stigmata” is thick with holy blood and a ragged pulse while reverberating in its own mysticism; the unsettling vignette “Incense At Abu Ghraib” references the Iraqi prison where music was used literally as one of many barbaric methods to torture religious detainees. The figure on the cover of the record recalls those scenes of torture, too, though it reframes the infamous imagery with the eye of a museum curator, a monument to the faithful and brutalized. Having long explored Brutalism as an aesthetic movement, here Hecker confronts the ways that violence, severity, and force play out in our human reality. It is to his credit that despite the darkness and tension on Virgins, he still manages to infuse these sounds with a sense of transcendence, particularly on “Amps, Drugs, Harmonium” and album closer “Stab Variation,” but it’s the kind of transcendence that can only be reached through fertile extremes.

2. Harmony In Ultraviolet (2006)

Harmony In Ultraviolet marks a culmination in Hecker’s career, plain and simple. Released the same year as his final Jetone release (the aptly-titled Sundown) before putting that project to bed, Ultraviolet saw him realize a thesis he’d been working on since embarking on his eponymous explorations. Even the title of the record implies a kind of peace – a stasis reached, in this case, between the music’s more obvious elements and those that cannot be experienced directly, but still exist, like invisible rays of light. The unseen had always been a concern of Hecker’s, and here he makes reference to everything from electromagnetic radiation to Victorian-era demons (soft-focus slow-burner “Spring Heeled Jack Flies Tonight”) to Greek myths (the undulating, soul-crushing “Chimeras”) to a 1979 invention that allegedly allowed its developers to converse with spirits (the otherworldly, ecstatic “Radio Spiricom”). Beneath those literal inspirations are the sonic dichotomies that Hecker had been flirting with on his prior releases – a melodic shimmer obfuscated by the pulse and fuzz of sense-tickling static.

Four years after Ultraviolet’s release, Jennifer Allen would coin the term ‘autonomous sensory meridian response’ in a Facebook Group, giving a name to the spontaneous, almost orgasmic tingling of the nervous system experienced by thousands of people. ASMR, as it is more commonly referred to, is triggered by things like whispering voices, paper tearing, and scalp massage and is described as feeling like “static;” the acoustic triggers read like a checklist Hecker might have used when building these first four albums. It’s almost as if he meticulously catalogued which elements of his prior recordings set off these sensations most successfully, eventually offering Ultraviolet as an end product that would not only trigger ASMR, but also translate the feeling of it for those who don’t naturally experience it. As such, Ultraviolet does this more effectively than anything he had previously produced, once again highlighting something unseen and immeasurable. Now, there are entire YouTube channels dedicated to inducing ASMR, but for a long time, Hecker was the singular artist to plumb those concepts and sounds, and though he hasn’t said as much, it can’t be a coincidence. This is a man with a PhD in the cultural history of sound – not music, but sound – after all.

Albums made before and after each have their own unique distractions from these effects, but on Ultraviolet, they are stripped away to one essential function. Hecker had to make this record before he could even think about making his more dynamic recent works (Ravedeath, Virgins, and Love Streams), though that’s not to say Ultraviolet isn’t itself dynamic. It is both restless and stoic at turns, obvious and subtle. Not only does it work as a continuous noise symphony, it also works on a track-by-track basis. The faint heartbeat wrapped in tender churn of “Dungeoneering,” the blown-out strains punctuating the atmospheric hiss of the “Whitecaps Of White Noise” suite, and its grandiose bookends, opener “Rainbow Blood” and its mirror-twin closer “Blood Rainbow;” each is its own perfect soundtrack. If the approach seems too methodical (the one criticism Hecker’s detractors like to trot out), then it’s almost ironic that Ultraviolet is a record that must be felt to be truly heard, its glory always just below its surface.

1. Ravedeath, 1972 (2011)

After nearly a decade of playing with elements that came to define not only his sound, but his ethos, Hecker made Ravedeath, 1972 – his most arresting work, a perfect storm of conceptual, structural, and sonic elements that combined everything he’d experimented with up to that point. Recorded in a hundred-year-old church in Reykjavík discovered by album engineer (and longtime co-conspirator) Ben Frost, the album features three separate song suites alongside a handful of interstitial stand-alone tracks, much like the formats he explored on Haunt Me and Harmony In Ultraviolet. Here, he combines instrumental elements (piano, guitar, and most notably, pipe organ) recorded within the church, manipulated and distorted over the course of a month in his studio back in Montreal. This hybrid of live recording and studio technique hearkened back to piano-driven LPs Mirages and Radio Amor, and foretold the direction he would take with Love Streams and Virgins later.

But it was likely the record’s potent concept that catapulted Hecker out of obscurity and allowed him to make those critically acclaimed follow-ups. Most of his records to that point were concerned with an overarching theme of some sort, but none so perfectly expressed as Ravedeath. The record pivots on the degradation of music, and everything – from the photo of MIT students pushing a piano off a roof in 1972, to the methods with which he attacked the original instrumentation – reflects that. His studio manipulations of the church organ give it a literal feeling of decomposition, much like William Basinski’s 2003 opus The Disintegration Loops, notably on album opener “The Piano Drop.” But he’s also exploring heady ideas about how people interact with music.

As listeners, we suffer from a glut of music that is not very thoughtful, even trite – hence the “Hatred Of Music” suite that appears mid-record. Operating for so long within a genre that, by the connotations of its very name — “ambient” — relegates it to background music, the haunting “In The Air” suite that finishes out the album reminds us that we’re surrounded by music, all the time, whether it’s that earworm we overhear at a shopping mall or the echo of it in our brains afterward. Even when pop music is used in dramatic television or movies, it’s a cheapened, degraded snippet, despite its cinematic purpose. Hecker has spent his career collaging the degraded snippets into something profound on both sensory and technical levels.

And then, there’s Hecker as creator, oft-described as enigmatic, inserting himself into the melee for once, on the shoegazey “Studio Suicide, 1980″ or wistful “Analog Paralysis, 1978,” both of which serve as reminders of the labor required to bring Ravedeath into being. The result is Hecker’s “Sir Duke” moment, a true artist making music about music, and it hits like the force of a baby grand thrown from the top of a tall building.