It was the first mosque to be built in Egypt, founded by the commander of the Arab troops. It was built in 21 A.H/641 A.D. The mosque also known as Taj al-Jawami’ or the Crown of the Mosques. The mosque’s importance today is that it indicates where Amr’s house, built near the original mosque.
The original building, much smaller than the present one. The original mosque had no minaret and no pulpit. Its floor wasn’t paved and probably was supported by palm trees, the roof was very low.
Stories mentioned that Amr set up a pulpit later to be well heard. However, caliph Omar Ibn al-Khattab rebuked him and ordered to remove it.
The additions:
1. The viceroy Maslama Ibn Mukhallad, ordered to enlarge the mosque, the  mosque was enlarged from north and west and added “the rahba” to the west side. He ordered to add 4 minarets to the 4 corners of the mosque and taking the shap of towers.
2. The Umayyad governor Abd al-Aziz Ibn Marawan ordered to pull down the mosque from the southern side.
3. The governor Qurra Ibn Shurayk enlarged the mosque from east and north, a concave niche and a new wooden pulpit were added.
4. A new area was added to the north-west of the mosque by al-Salih Ibn Ali.
5. Abdullah Ibn Tahir doubled the area of the mosque from the southern side.