This mosque is the oldest and largest mosque in Tunisia, in the 4th most holiest city of Islam (after Mecca, Medina & Jerusalem) which accords it a very, very important status. It also has a very fascinating architectural history that started in 670AD when the city was first founded. From its humble beginnings, the mosque eventually grew to its present size after many renovations under the numerous rulers in 8th, 9th, 13th, 14th, 17th, 18th and 19th century. This resulted in a rich combination of different design influences. The minaret is the world's oldest standing minaret, where the lowest storey is believed to date back to 730AD and, is interestingly made of stone blocks taken from classical Roman buildings. The beautiful marble columns were also removed from Roman & Byzantine sites. The floors of the courtyard are made of white marble in which a white stepped sundial stands. Several well heads are located in the courtyard, (two next to the sundial for example), where water that has been collected from the rains, is drawn.