what are some of the most famous landmarks in the second city?
The obelisk, Valens Aqueduct, Column of Constantine, Church of the Saints Sergius and Bacchus
Istanbul
 The obelisk erected by Theodosius in the Hippodrome of Constantinople is still visible in Sultanahmet Square, and a section of the Valens Aqueduct, constructed in the late 4th century, stands relatively intact at the western edge of the Fatih district. The Column of Constantine, erected in 330 CE to mark the new Roman capital, stands not far from the Hippodrome.

Early Byzantine architecture followed the classical Roman model of domes and arches, but improved upon these elements, as in the Church of the Saints Sergius and Bacchus. The oldest surviving Byzantine church in Istanbul—albeit in ruins—is the Monastery of Stoudios
when was the byzantine empire born what was it originally called 5th century AD and was called Eastern Roman Empire, or Byzantium and when did it fall? 1453 which battle or event marked the fall of this empire? A six-year-long civil war followed by attack from Sultan Mehmed's army did he conquer other territories as well? Yes. Anatolia and in Southeast Europe as far west as Bosnia where is the first area located in present day terms? Turkey who were the oldest known inhabitants of this region? Mesopotamian-based Akkadian Empire what is the present day capital of the country? Ankara can you name some of the other major cities here? Istanbul were any of these cities associated with the first empire you were discussing? The Ottomans made the city of Ankara the capital first of the Anatolia Eyalet and then the Angora Vilayet
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Istanbul [SEP] Architecture
Among the oldest surviving examples of Ottoman architecture in Istanbul are the Anadoluhisarı and Rumelihisarı fortresses, which assisted the Ottomans during their siege of the city. Over the next four centuries, the Ottomans made an indelible impression on the skyline of Istanbul, building towering mosques and ornate palaces. The largest palace, Topkapı, includes a diverse array of architectural styles, from Baroque inside the Harem, to its Neoclassical style Enderûn Library. The imperial mosques include Fatih Mosque, Bayezid Mosque, Yavuz Selim Mosque, Süleymaniye Mosque, Sultan Ahmed Mosque (the Blue Mosque), and Yeni Mosque, all of which were built at the peak of the Ottoman Empire, in the 16th and 17th centuries.