The modern town of Ausim (pronounced Ashim) lies on the western edge of the delta cultivation around 12km north-west of Cairo, between the Rosetta and Damietta branches of the Nile. Nothing now remains of the ancient town of Khem, called Letopolis by the Greeks, which was situated in this area.

The town of Khem is known from Old Kingdom texts and is also mentioned in Middle Kingdom Coffin Texts as a centre of worship of the god Horus Khenty-Irty, or Horus Khenty-Khem, one of many local aspects of Horus. The god is mentioned on a panel from the South Tomb of the Step Pyramid at Saqqara as 'Horus of Khem' in an inscription which uses the archetypal Lower Egyptian Shrine as the determinative for the cult place of Horus at Letopolis. It is interesting that this is the only panel in the South Tomb where the King Djoser-Netjerikhet wears the red crown of Lower Egypt.

During the Graeco-Roman Period Letopolis was the capital of the 2nd Lower Egyptian Nome whose symbol included the Horus falcon. Only fragments of monuments have so far been recovered from the site, including blocks bearing the names of Late Period Kings Necho II Wehemibre, Psamtek II Neferibre, Hakor Khnemmaatre and Nectanebo I Kheperkare. Nothing has been found from the earlier periods when there must have been an important cult centre here.