Possible Clues:

• 1979 U.K. album certified 23 times platinum in the U.S
• Pink Floyd album with bricks on its cover
• See 9 Across, 23 Across, 12 Down
• Groundbreaking Pink Floyd album
• Pink Floyd album
• See 18
• Pink Floyd epic
• The Floyd's greatest structure
• Gregory Isaacs is a cool one