The Topkapı Palace in Istanbul served for centuries as the residence and government seat of the sultans and was the administrative center of the Ottoman Empire. The construction of the palace, which is divided into four courtyards, began shortly after the conquest of Constantinople in 1453. Today, the complex houses a museum, which features porcelain collections, manuscripts, weapons and other objects from the Ottoman Empire, as well as Islamic relics, such as one of the oldest copies of the Koran.
Topkapı Palace, color photography, 2011, photographer: Carlos Delgado; source: Wikimedia Commons https://commons.wikimedia.org/wiki/File:Topkap%C4%B1_-_01.jpg, attribution - transfer under the same conditions 3.0 Unported (CC BY-SA 3.0) https://creativecommons.org/licenses/by-sa/3.0/deed.de.