One of the most popular, and analyzed, rock albums ever is undoubtedly Pink Floyd's 1979 sprawling masterpiece The Wall. Although the definitive version remains the aforementioned studio album, there has also been a 1982 movie (starring a pre-Live Aid Bob Geldof), and two separate live albums -- one by Roger Waters in 1990 (The Wall: Live in Berlin, 1990) and the other a delayed release of Pink Floyd performances from the early '80s (2000s Is There Anybody Out There? The Wall: Live 1980-1981). So you think that would be the last we heard from The Wall, right? Think again. A multitude of classic rockers/prog rockers have united to cover The Wall in its entirety, under the title Back Against the Wall. Led by producer Billy Sherwood, a rotating case of musicians was assembled to make anyone with a well-worn copy of Tales of Topographic Oceans drool with excitement -- Yes' Rick Wakeman, Chris Squire, Alan White, and Geoffrey Downes; King Crimson's Adrian Belew, Tony Levin, and John Wetton; Styx's Tommy Shaw; ELP's Keith Emerson, and Jethro Tull's Ian Anderson, among countless others. Interestingly though, it can be argued that The Wall was Pink Floyd's least "progressive" album, as the group focused on tight song structures -- obviously inspired by the then burgeoning new wave and punk movements. The performances are expectedly spot-on (and it's quite impressive how they re-created all the sound effects/spoken word bits so precisely), and stick very close to the originals -- except for a Chris Squire-led take of "Comfortably Numb," which adds a few extra bits. With an ever-increasing overabundance of versions of The Wall to choose from, you've got to wonder if Back Against the Wall was necessary at all.