Longest continuous playing songs


I like (and looking for) continuous playing music, it could be one song or a group of songs that play uninterrupted, the longer, the better. Does anybody have any suggestions?

Thanks for any suggestions,

Steve
sc2
Many good suggestions, one not hit yet is the Beastie Boys Paul's Boutique, it is one continuos groove, and like Pink Floyds Meddle, starts where it ends so it could play on forever.

Rush 2112 is pretty long as wel.
Mike Oldfield is famous for long running songs. My favorite is "Ommadawn" which runs for 36+ minutes. Tubular Bells runs 48 minutes.
Blue Room-The Orb. This is the infamous 39:57 minute long song they put out in response to the 40:00 cap that was put on singles in the 90's. It's pretty great and it's never boring.
Enigma MCMXC. Is seems to be one long continuous tune. Recorded very well for being done in analog then put on to CD. Gotta be in the mood for it though.
Happy listening, John