Pete Seeger was primarily known for his incredible musicianship, but that legacy extends itself into advocacy about the environment, classism, and racism among other injustices. His song “We Shall Overcome,” became an anthem for Civil Rights movement demonstrations in the ’60s. Before he passed away in 2014 at 94 years old, the legendary songwriter stood in solidarity with the Occupy Wall Street movement in 2011. Today, on what would have been his 100th birthday, the Smithsonian is releasing a celebratory box set that includes 20 previously unheard songs.

The box set includes a large-format 200-page book with hundreds of essays, commentary, photographs, history, and liner notes. The collection itself is six discs of classic and unreleased music recorded at various points during Seeger’s massive six-decade career. Taken largely from unearthed reels from the vaults of the label Smithsonian Folkways, the tracks were produced by Jeff Place and Robert Santelli. The duo also produced Woody at 100 and Lead Belly: The Smithsonian Folkways Collection, completing a trilogy commemorating three of Folkways’ most iconic recording artists.

Stream the whole 137-track collection below.

Pete Seeger: The Smithsonian Folkways Collection is out now. Purchase and stream it here.