Goodbye 20th Century is a double album of covers of Avant-garde recordings by Sonic Youth and collaborators. SYR4 features works by avant-garde classical composers such as John Cage, Yoko Ono, Steve Reich, and Christian Wolff played by Sonic Youth along with several collaborators from the modern avant-garde music scene, such as Christian Marclay, William Winant, Wharton Tiers, Takehisa Kosugi and others. The album received mixed reviews, but most critics praised the group's efforts at popularizing and reinterpreting the composers' works. Unlike in other SYR releases SYR4's liner notes are written in English.