Credit: David M. Benett/Getty Images

No, it’s not the dark side of the moon. Founding Pink Floyd bandmembers Roger Waters and Nick Mason unveiled a plaque at the University of Westminster in London (formerly called London Polytechnic) on Thursday to commemorate the group’s 50th (!) anniversary.

The group, which originally called themselves Sigma 6, was rounded out by keyboardist Richard Wright, who died in 2008, and guitarist David Gilmour, who did not join the ceremony as he was not a founding member (he joined the group in 1967). A video of the event and an interview with Mason and Waters is streaming below.