J. P. Dodson's comments about the Canon EOS mount lenses not being usable on an older FD camera like an AE-1, or even a F-1 is, of course correct. However, precisely because the FD lenses won't work on a Canon DSLR, most are available for very, very low prices. Some of these lenses are excellent and some of them, debatably, have not been bettered, even by many current EOS designs.
I still have a working F-1 with a full complement of FD lenses, and I still have some 30 X 40 inch "razor sharp" monochrome landscape prints taken with that (tripod-mounted and mirror-locked) F1 using a Canon 24 mm F 2.8 FD and Pan-X film. I don't honestly think I can match the print quality with my 50D and 24mm f 1.4 "L" lens.
Aw, the good old days!