Reservoir re-housed, historical artifacts moved or rare environments relocated. Examples include the temples of Abu Simbel (which were moved before the construction of the Aswan Dam to create Lake Nasser from the Nile in Egypt), the relocation of the village of Capel Celyn during the construction of Llyn Celyn, and the relocation of Borgo San Pietro of Petrella Salto during the construction of Lake Salto. Construction of a reservoir in a valley will usually need the river to be diverted during part of the build, often through a temporary tunnel or by-pass channel. In hilly regions, reservoirs are often constructed by
Romanian air tours over Africa Philae Island, and hedgehopped over the temples of Ramesses II and Nefertari at Abu Simbel. They entered Sudan and stopped at the customs point of Wadi Halfa. They flew over the second cataract, then cut the meander of the Nile through the desert, along the Wadi Halfa– Abu Hamad railway line up to Railway Station No. 6, where they overnighted. The following day they flew over the fifth cataract, Atbara, and after the sixth cataract they reached Khartum, where they stayed for two days as the engine of Pantazi's aircraft needed overhauling. After a short stage to Kosti, they reached