Ain Shams (also spelled Ayn or Ein - , , ) is a district in the Eastern Area of Cairo, Egypt. The name means "Eye of the Sun" in Arabic, referring to the fact that the district contained the ruins of the ancient city of Heliopolis, once the spiritual centre of ancient Egyptian sun-worship, and settled since 3100 BCE following the Predynastic Period. However, administratively the visible ruins today lie in the district of al-Matariya.
Ain Shams is divided into six shiakhas (census blocks/quarters), which had a total of 614,391 residents in the 2017 census, making it the third most populous district in Cairo: