Heliopolis was one of the oldest cities of ancient Egypt, the capital of the 13th Lower Egyptian nome that was located five miles (8 km) east of the Nile to the north of the apex of the Nile Delta. Heliopolis has been occupied since the Predynastic Period, with extensive building campaigns during the Old and Middle Kingdoms. Today it is mostly destroyed; its temples and other buildings were used for the construction of medieval Cairo; most information about the ancient city comes from textual sources.
Beneath a maze of busy narrow streets of a middle and lower-class district, lie vast hidden remains of ancient Heliopolis about fifteen to twenty metres down. This ancient Egyptian site lies predominantly in the northern Cairo suburb of Al-Matariyyah, and also covers the districts of Ain Shams and Tel Al-Hisn east of the Nile. It also straddles the Cairo Metro line 1–2 km west of the edge of the 20th century modern Heliopolis, a suburb in the district Masr al-Gidedah .
The site of Heliopolis has now been brought for the most part under cultivation and suburbanization, but some ancient city walls of crude brick can be seen in the fields, a few granite blocks bearing the name of Ramesses II remain, and the position of the great Temple of Re-Atum is marked by the Al-Masalla obelisk. Archaeological sites below including recent tomb discoveries.
The only surviving remnant of Heliopolis is the Temple of Re-Atum obelisk located in Al-Masalla of the Al-Matariyyah district. It was erected by Senusret I of the Twelfth dynasty, and still stands in its original position. The 68 ft (20.73 m) high red granite obelisk weighs 120 tons (240,000 lbs)