Théodule Devéria help Mariette read inscriptions in Cairo and its surroundings. He tried to accurately document the archaeological sites using drawings, stampings and photographs. His calotype pictures from this trip are often poor in quality, showing a lack of technical skills. In 1860 he was appointed preserving assistant at the Louvre's Department of Egyptology. He revisited Egypt in 1861–62, traveling up the Nile to Philae at the First Cataract, and into Nubia to the Abu Simbel temples. After returning he helped Mariette prepare descriptions of the excavation in Egypt in 1850–54 for publication. In November 1864 Devéria met the future oriental scholar
Abu Simbel temples as a lasting monument to the king and his queen Nefertari, and commemorate his victory at the Battle of Kadesh. Their huge external rock relief figures have become iconic. The complex was relocated in its entirety in 1968 under the supervision of a Polish archaeologist, Kazimierz Michałowski, on an artificial hill made from a domed structure, high above the Aswan High Dam reservoir. The relocation of the temples was necessary or they would have been submerged during the creation of Lake Nasser, the massive artificial water reservoir formed after the building of the Aswan High Dam on the Nile River.