Your tour begins as you gather with your guide at the Fountain of Ahmed III outside the entrance of the Topkapı Palace. From there, enter the museum to begin your exploration. The Topkapı Palace is a large museum in Istanbul, Turkey. In the 15th century, it served as the main residence and administrative headquarters of the Ottoman sultans. Construction began in 1459, ordered by Mehmed the Conqueror, six years after the conquest of Constantinople. Topkapı was originally called the "New Palace" to distinguish it from the Old Palace in Beyazıt Square. It was given the name Topkapı - meaning Cannon Gate, in the 19th century. The complex was expanded over the centuries, with major renovations after the 1509 earthquake and the 1665 fire. The palace complex consists of four main courtyards and many smaller buildings. Female members of the Sultan's family lived in the harem, and leading state officials, including the Grand vizier, held meetings in the Imperial Council building. After the 17th century, Topkapı gradually lost its importance.