Amr Iban El-As chose the plain close to the fortress of Babylon, to build the new arab capital in Egypt. Here he built his mosque which still stands though repeatedly altered or restored and here he began and foundation of the city which he called El Fustat which remained the capital of Egypt for more than three centuries, until El Kahira (Cairo) was founded close by 969. The new capital spread rapidly and soon became one of the chief cities of the Mohamedan Empire. The houses were at first of one storey but later they grew bigger and higher until some of them consisted of five stories.From El-Fustat, Abdul Aziz Ibn Merwan moved to Helwan (near Memphis, on the opposite bank of the Nile). Here, he planned the city, built houses, mansions and mosques, planted orchards and palm groves, and caused a Nilometer to be erected.

The Ommeyade governors generally lived at Fustat. The Abbassid governors, on the other hand, built a new official capital (a military suburb) on the plain to the north east of Fustat, where soldiers of some of the Arab tribes had formerly built houses of defenses. Saleh Ibn Ali (an Abbassid general) camped there in 750. His lieutenant built houses and El-Askar became the official residence of the governor, his guard and ministers. Another palace, called Kubbat-el-Hawa (Dome of the Air) was built on the spur of the Mokattam Hills, where the Citadel of Cairo now stands. The governors often resorted seeking cool breezes.
The Remains of El Fustat City can be seen in the eastern Nile bank. The Fustat City had been established by Muslims to be the capital of Islamic Egypt. They provided the city with all the water supply and sanitation services that made it excel many other city in that time. The city was also distinguished by its glassware and ceramics and the magnificent style of decoration but its only flaw is the lack of strong frots to protect it from the exterior attacks. In 1168, during the war of Crusaders , the city had been totally burnt, and none of its marvelous buildings survived. In spit of the absence of any monument, there are some remains of the domestic architecture that had been used in the old city. Many attempts for reestablishing the city have been made, but unfortunately it could not regain its old glamorous style. Now there are only few blocks and bases of mudbrick houses scattererd in vasst mound.