Ottoman architecture is an architectural style that developed under the Ottoman Empire over a long period, undergoing some significant changes during its history. It began in northwestern Anatolia around the end of the 13th century and developed from earlier Seljuk Turkish architecture, with influences from Byzantine and Iranian architecture along with other architectural traditions in the Middle East. Early Ottoman architecture experimented with multiple building types over the course of the 14th to 15th centuries, progressively evolving into the classical Ottoman style of the 16th and 17th centuries. This style integrated the Ottoman tradition with influences from the Hagia Sophia, resulting in monumental mosque buildings focused around a high central dome with a varying number of semi-domes. The most important architect of the classical period is Mimar Sinan, whose major works include the Şehzade Mosque, Süleymaniye Mosque, and Selimiye Mosque.