Delve into the fascinating history of Old Istanbul and take in the opulence and extravagance of the Topkapi Palace, residence of the Ottoman sultans for 400 years and home to some of the most important relics of the Muslim world and visit the tombs of former Sultans at Hagia Sophia's courtyard. Wander around Topkapi Palace's immaculate grounds Admire a vast collection of priceless artefacts Visit the Sultans' tombs at Hagia Sofia