The great Mosque or Mosque of the olive, is the largest and oldest mosque (built in the year 732) in the capital and the second in Tunisia after cyranski. There is an ancient legend, which tells that, on the spot where now stands the mosque, once grew a wonderful olive tree, and before there was a Roman forum. The mosque was repeatedly reconstructed and expanded.

For ritual ablutions in the mosque is used only rainwater, which is collected in special tanks. Noteworthy is a very beautiful dome of the mosque. Spacious and dark prayer hall of the mosque is decorated with chandeliers of Venetian glass. Arch hall is based on the magnificent ancient columns with carved capitals.

The mosque is surrounded by many madrasas. Here in the fourteenth century worked famous Tunisian educator Ibn-Khaldun, which is called the "father of sociology".