Ottomans achieved their highest level of architecture when they encircled the Constantinople which is todays Istanbul and before hand, they were setteled all over the western Anatolia. They aimed to spread the Islamic culture and this gave start to building imarets which include a mosque, a tomb, a bath, a religious school, and a soup kitchen. The Ottomans started placing dome to every structure they found important. The structure had a very important feature: symmetry. The Byzantine masterpiece, the church of Hagia Sophia, exerted a commanding influence on the design of Ottoman mosques, placed on the many hilltops of Istanbul. Sinan, the chief architect, impressed from Hagia Sophia and Byzantine samples and established an Ottoman style.
The beehive domes of Seljuk’s was special for Anatolian region and actually the Ottoman architecture was emerged from imitating the masonry of Armenian churches and Persian like arcades. Orhan Gazi Mosque become a model. It has a reverse-T shape plan overlooking to the central markets. On the front facade has pointed arches as it is seen in other Islamic structures. The mosque had a fountain for the use of religious needs in an octagonal form. The two central domes of the mosque dominates an axis inside through Mecca.
Green mosqueis also one other mosques built during Ottoman Architecture. It is in Bursa and it has similar features with Orhan Gazi Mosque. There is reversed-T shaped plan and it has great proportional and symmetrical system inside it. It resembles the Byzantine protocol used by Umayyads as well.There is also colored clerestory lightnings which can also be seen in Gothic Architecture. Unlike these two mosques, Ulu Cami doesn’t have a reversed shaped plan rather than having revered-T shaped plan, it has a hypostyle hall. I found this very interesting because it is, as Green Mosque, in Bursa(other mosques built after this one also don’t have any revered-T shaped plan). And add to these each bay carries a rounded dome and this later becomes a standard units in Ottoman arch system.