Half a century ago, as young students in London, Roger Waters, Nick Mason, Richard Wright and Syd Barrett formed Pink Floyd.

A lot has changed since they released their first album in 1967.  David Gilmour joined the band. Barrett left due to mental health issues. They went on to become one of the most successful commercial acts of all time. Richard Wright passed in 2008.

But even after 50 years of ups and downs, Pink Floyd maintains its status as one of the world’s most popular, influential bands. Their newest album, The Endless River debuted at #1 in several countries and, upon its release in 2014, became the #1 pre-ordered album of all time on Amazon in the UK.

On Thursday, Roger Waters and Nick Mason took part in a ceremony that commemorates the band’s formation 50 years ago, unveiling a Heritage Plaque in London, and reminiscing about the early years.

Watch a short video clip from the ceremony here.

David Gilmour did not attend, but that’s understandable, since he didn’t join the band until December of 1967.

WATCH: David Gilmour discusses The Wall with CDJ’s Paul Rappaport