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
Abu Simbel temples erosion of the sandstone by desert winds. However the proposal, though acknowledged to be extremely elegant, was rejected. The salvage of the Abu Simbel temples began in 1964 by a multinational team of archeologists, engineers and skilled heavy equipment operators working together under the UNESCO banner; it cost some US$40 million at the time (equal to $300 million in 2017 dollars). Between 1964 and 1968, the entire site was carefully cut into large blocks (up to 30 tons, averaging 20 tons), dismantled, lifted and reassembled in a new location 65 meters higher and 200 meters back from the river, in