Guided sightseeing today includes a morning visit to the 15th-century Topkapi Palace, home of the Ottoman Sultans for almost four centuries. One of the world's largest surviving palaces, it was built under the orders of Sultan Mehmed II, a few years after he conquered Constantinople. Enjoy a glimpse of the imperial life of the sultans as you walk through the grand courtyards, pavilions, and ceremonial rooms that display an impressive collection of artifacts and treasures. And venture into the Harem, where over 400 exquisitely decorated rooms were shared by the sultan, his wives, concubines, and children. After lunch in the old city, visit Hagia Sophia Grand Mosque, one of the world's greatest architectural achievements. Built in the 6th century under Emperor Justinian I, Hagia Sophia stood as the largest cathedral in the world for nearly a thousand years. Its soaring dome, immense marble pillars, and intricate mosaics tell the story of its layered history as a Byzantine church, an Ottoman Mosque, a museum, and now, once again, a mosque. Gaze up at the vast dome, suspended seemingly weightless above the cavernous space, and take in the interplay of Christian and Islamic elements – glowing calligraphic medallions juxtaposed with ancient depictions of Christ and the Virgin Mary. This evening, join us for a special dining experience in the old city of Istanbul, exclusive to Tauck guests.