A mix of old and new, as roads now travel through the arches of the 4th-century Valens Aqueduct.
Dolmabahçe Palace, an example of the Ottoman Baroque architecture.
A section of the Valens Aqueduct, constructed in the late 4th century to carry water to the city, stands relatively intact over 970 meters (3,200 ft) in the west of the Fatih district. Similarly, the Walls of Constantinople, which were erected in stages well into the Byzantine period, are still visible along much of their original 4-mile (6.4 km) course from the Sea of Marmara to the Golden Horn.Finally, the Column of Constantine, erected in 330 AD to mark the new Roman capital, still stands not far from the Hippodrome.Early Byzantine architecture followed the classical Roman model of domes and arches, but further improved these architectural concepts, as in the Church of the Saints Sergius and Bacchus. The oldest surviving Byzantine church in Istanbul (albeit partially in ruins) is the Stoudios (mrahor) Monastery, which was built in 454.[88] Other extant structures from the early Byzantine period include the Hagia Irene, initially the first church in the new capital, and the Prison of Anemas, which was incorporated into the city walls. After the recapture of Constantinople in 1261, the Byzantines constructed two of their most important churches, Chora Church and Pammakaristos Church. Across the Golden Horn, the Genoese contributed Galata Tower, then the highest point in the citadel of Galata. Still, the pinnacle of Byzantine architecture