Ummagumma is Floyd at their most cosmically adventurous—and one of the most joyously freaky records ever released by a major label. On the live half, the band attacks already-trippy material like the swirling "Astronomy Domine" with an even more ominous, otherworldly feel. The studio recordings are solo efforts by all four band members, crafting heady prog-rock suites and mind-blowing avant-garde sound collages. In the middle sits Roger Waters' chiming "Grantchester Meadows," pointing the way to the delicate, atmospheric tunes that would become Floyd mainstays.