The island temple was built during the Ptolemaic Kingdom. The principal deity of the temple complex was Isis, but other temples and shrines were dedicated to other deities such as Hathor. Egyptologists believe that Philae was the last active site of the native ancient Egyptian religion, and that the last Egyptian hieroglyph was written there in the late fourth century.
The temples had been practically intact since the ancient days, but with each inundation the situation worsened and in the 1960s the island was submerged up to a third of the buildings all year round.
In 1960 UNESCO started a project to try to save the buildings on the island from the destructive effect of the ever-increasing waters of the Nile. First, building three dams and creating a separate lake with lower water levels was considered.
The monuments were cleaned and measured, by using photogrammetry, a method that enables the exact reconstruction of the original size of the building blocks that were used by the ancients. Then every building was dismantled into about 40,000 units, and then transported to the nearby Island of Agilkia, situated on higher ground some 500 metres (1,600 ft) away.