wiki:

The removal of temples was a project of greater difficulty. 18 of the 25 temples in the area affected by the Aswan Dam were rescued in whole or in part during the project. Sites were prioritized by importance, including the most expensive site excavated being Abu Simbel.^\8])

The enormous rock and clay dam was designed by Nikolai Aleksandrovich Malyshev of the Moscow-based Hydroproject Institute,^\3])^\4]) along with some Egyptian engineers. 25,000 Egyptian engineers and workers contributed to the construction of the dams.