When does the Abu Simbel Sun Festival take place?
The event occurs twice a year - on the 22nd February and the 22nd October. When the temple of Ramses II was first built, the Sun Festival was celebrated a day earlier, on the 21st of February - reportedly the anniversary of Ramses' ascension to the throne, and on the 21st October, his believed birthday. The temple was built so that the inner sanctums were perfectly aligned with the sun's rays on just these two dates of the year - at all other times the inner sanctuary sits in darkness.
The construction of the Aswan Dam in the 1960's threatened to submerge Abu Simbel underwater, so the entire complex was moved in a painstaking operation to bring it 200 metres away from the high water line. The project cost millions of dollars but allowed this most famous of temples to survive, and Egypt to get the development it needed from the dam. Since the move, the Sun Festival now takes place a day later than in the time of Ramses II.