Abu Simbel is very special because it is a piece of Ancient Egypt left for us to see. It is also perfectly arranged so that twice every year, on the 22nd of Feburary and October the sunlight beautifully illuminates the back wall and the thrones of the four gods seated there.
The Abu Simbel Temples were created, at least in part, to celebrate Ramesses' victory over the Hittites at the Battle of Kadesh.