Correction to slim's (since deleted) w/u: the festival was not run continuously during the 1970s; there were a couple during 71-73, and then it was resurrected in 1979 (headliners were John Martyn, Steve Hillage and Peter Gabriel, although the best bit was arguably the half hour unamplified drum solo by the drummer from the Only Ones when the power went down) and has been run most years since then, although Michael Eavis takes a year off every now and then - inter alia 1996, 2001 (when foot and mouth disease would undoubtedly have done for it anyway) and 2006 - to resolve various local and security issues and to give the cows and villagers a break - although he has done very nicely from the festival, he thinks of himself first and foremost as a dairy farmer.
The festival site on Worthy Farm is not actually at Glastonbury, but at the Somerset village of Pilton (about half way between Glastonbury and Shepton Mallet, and within sight of that tit-shaped hill), and the real locals refer to it by that name. The vagaries of English June weather mean that the experience can be extraordinarily muddy, or you can pick up quite serious sunburn, or both. For recent editions much of the on-stage action has been televised by the BBC.