From Lars Arrhenius’ 8-bit-inspired tiles at Thorildsplan station to Ulrik Samuelson’s “ghost garden” at Kungsträdgården, and Björk and Åberg’s mural at Solna Centrum Station, artwork saturates Stockholm’s subway system. German photographer David Altrath explored the underground (or tunnelbana in Swedish) over several late nights last year, capturing images at a time that, “it seemed like I was the only person there,” he tells Wired. Altrath abandoned sightseeing in the city and instead traipsed the 94 stations that over 250 artists have decorated. The resulting images show off the varied pieces, as well as the architectural delights of the subterranean wonderland. See more at Wired.