The multi-unit mosque uses several domed-squares of similar size along the length of a mosque, or across its width, or both, with the central dome sometimes larger than the others. A style common in the Bursa period, and known as the "Bursa type", is like a duplication of the single-domed square, with one long space divided by an arch into two square bays that are each covered by a dome. A variation of this type has the room covered by one dome and one semi-dome, with additional side chambers. A multi-domed style derived from Seljuk architecture is that of the Ulu Camii, or Great Mosque, which consists of a number of domes of the same size supported by pillars.