Here's what wikipedia has to say about the caves (full article):
Ellora represents the epitome of Indian rock cut architecture.The 35 "caves" – actually structures excavated out of the vertical face of the Charanandri hills – comprised of Buddhist, Hindu and Jain cave temples and monasteries, were built between the 5th century and 10th century. The 12 Buddhist (caves 1-12), 17 Hindu (caves 13-29) and 5 Jain caves (caves 30-34), built in proximity, demonstrate the religious tolerance prevalent during this period of Indian history.
If you ever plan to visit India, I suggest you add this to your agenda. Highly recommended!
Here are some more photos
or see the entire set (73 photos).