In the summer of 1955 I saw an outdoor production of Aida at the Baths of Caracalla. I swear it ended with some chariots being pulled onto the stage by several white horses. Do they still have chariots and horses at the end? It was very dramatic, to say the least.
We are are the Baths of Caracalla in October, 09, and saw no evidence of a stage, seating or anything similar. If only a summer production, then we may have missed it completely.
Looks like they are doing Aida in August, from 2 Aug. to 9 Aug. http://en.operaroma.it/stagione/stagione_2010_2011/opere