It is the first mosque built in Egypt and the fourth in the whole world (642 AD) by Amr Ibn Al-As north of Babylon Fortress. It lies in El Fostat region. It is simple in design and represents schools of architecture from different periods. Its pillars were taken from palm trees trunks and covered with dry fronds. Renovations and extensions followed in the course of time. Its present planing consists of a central open space surrounded by four roofed side wings the biggest of which is the Qebla with its marble pillars of different styles. Inhabiting also the oldest Islamic University, it continued to impart its message through nine centuries.