The ancient Egyptian temple complex relocated in the 1960s to avoid flooding was Abu Simbel.
Abu Simbel consists mainly of two rock-cut temples built during the reign of Pharaoh Ramesses II in the 13th century BCE. The larger temple is dedicated to Ramesses and the gods Amun, Ra-Horakhty, and Ptah; the smaller temple honours Queen Nefertari and the goddess Hathor.
The temples faced submersion after Egypt began constructing the Aswan High Dam. Internationally coordinated rescue work cut the monuments into large blocks, moved them to higher ground, and reassembled them inside an artificial mountain between 1964 and 1968. The relocated complex was officially inaugurated on 22 September 1968.
The rescue campaign became a landmark in archaeological engineering and helped inspire the international heritage-protection system associated with UNESCO. Philae was also relocated because of the dam, but Abu Simbel is the best-known answer to this question.