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
Beethoven's 9th -- there used to be a rumor that the maximum capacity of CDs was picked so that all of Beethoven's 9th could fit on 1 CD. Also, many operas are several hours long -- ever fallen asleep during a Wagner performance, awoken a half-hour later and felt like you never left?
Why don't you use an iPod or iTunes. You can make your own mix and play for hundreds of hour non stop.
In-A-Gadda-Da-Vida by Iron Butterfly. At about 17 minutes, one of the longest classic single rock songs.