Throwback Thursday to May 1973, when artist Rockne Krebs shot lasers from the Museum’s East Terrace to mirrors along the Parkway every evening, from dusk until midnight, in a project called Sky Bridge Green. To see more pictures from this project and by Krebs, visit our current Minimalism installation.

Pictured: Installation photographs of Sky Bridge Green. May 1, 1973. Gelatin silver prints by Patrick Radebaugh. Philadelphia Museum of Art, Archives, Marketing and Public Relations Department Records.