Longest continuous playing songs

I was driving over to Santa Monica for sushi tonight. About a 30 minute drive. Some college station fron Cal State Northridge was playing Grateful Dead live from Winterland in Nov. 1973. The tune lasted the entire drive.

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.

Mike Oldfield "Amarok"

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.