One of Istanbul's more fascinating sights, the small but well-done Mosaic Museum is reached via an entrance halfway through the Arasta Bazaar and houses an excellent display of early Byzantine mosaics—some presented in situ—from the Great Palace of Byzantium, the imperial residence of the early Byzantine emperors when they ruled lands stretching from Iran to Italy and from the Caucasus to North Africa. This enormous residence reached from here all the way down to the sea and consisted of several terraces, with various palaces, churches, and parks, almost all of which are now gone. Only scant ruins remained by 1935, when archaeologists began uncovering what is thought to have been the floor of a palace courtyard, covered with some of the most elaborate and delightful mosaics to survive from the era, most dating to the 6th century. They include images of animals, flowers, hunting scenes, and mythological characters—idylls far removed from the pomp and elaborate ritual of the imperial
As you walk the streets of Sultanahmet you'll see many fragments of masonry and brickwork that were once part of the palace, and several cisterns have been found under hotels and carpet shops, some of which are open to visitors. New excavations on property owned by the Four Seasons Hotel are supposed to open as an archaeological park. Down by the water, there are extensive, overgrown remains of the facade of the Bucoleon Palace, the private quarters of the emperors from the 6th to 11th centuries, which are gradually being shaken apart by the passing train line.