Hamunaptra is the name of a fictional city in the 1999 horror/action film, The Mummy. In the 1999 film, The Mummy, Hamunaptra is an ancient Egyptian city hidden deep in the desert some distance from Thebes and is the primary setting for the story. Unlike many of the real places mentioned in the movie, this Hamunaptra is purely fictional.
In the film, Thebes is identified as the "City of the Living" while Hamunaptra is the "City of the Dead, ancient burial site for the sons of pharaohs, and resting place for the wealth of Egypt." This coincides only loosely with the actual Wadi el-Muluk, the Valley of the Kings on the opposite side of the Nile from ancient Thebes. Being to the west, where the sun set, this valley was considered the realm of the dead. King Seti I, who is depicted in the film, was entombed there.
Hamunaptra is depicted as containing two books central to the film's plot. One is the golden Book of Amun-Ra, "The Book of the Living", hidden beneath the statue of Horus. "It contains within it all the secret incantations of the Old Kingdom." The other is the black Book of the Dead, hidden beneath the statue of Anubis. The Book of the Living can take life away while the Book of the Dead can give it back. It is the latter that Imhotep, high priest of King Seti I, uses in his attempt to resurrect his true love Anck-su-namun meaning "Life's mystery" or "hidden one."
Also in this city is the preparation room where mummification is carried out. And hidden deep is a large underground chamber holding "the wealth of Egypt." To protect this treasure, however, the entire city is hidden behind a desert mirage and is only revealed to travellers at sunrise. This entire necropolis was "rigged to sink into the sand on Pharaoh's command," causing the city to disappear under the desert, putting the treasure permanently out of reach. Near the end of the film this defence is accidentally triggered and the city begins to sink. During the second film you can see workers digging to find it and it's now hidden treasures.
With the passage of time, Hamunaptra became a lost city, the subject of legends. As a result, by the 1920s, the decade in which most of the film's action takes place, its existence is doubted by serious scholars.