There is no substitute: Echoes, from Pink Floyd's 1971 album, Meddle. Sadly, this album - and Animals - are often overlooked for the big three - Dark Side, WYWH, and The Wall.
Epic is a word that is thrown around a lot these days, but this song certainly is. It's mind melting. The jam section is tops. I cannot turn up these headphones loud enough. I think I may check out the live version from Live at Pompeii next.