This city, which may have been founded in the early 7th century BC as a colony of Megara, was besieged by Septimius Severus in AD 193.  He tore down its walls, which may have helped the Goths in their invasion fifty years later.  After being liberated from the Persians in 478 BC, it acquired territory in neighboring Mysia and Bithynia. Its revolts against Athens were critical because of its import
This city, which may have been founded in the early 7th century BC as a colony of Megara, was besieged by Septimius Severus in AD 193.  He tore down its walls, which may have helped the Goths in their invasion fifty years later.  After being liberated from the Persians in 478 BC, it acquired territory in neighboring Mysia and Bithynia. Its revolts against Athens were critical because of its importance to Athens' food supply; it revolted again in 411 but was recaptured along with neighboring Thasos and Chalcedon [cal-SEE-dunn].  FTP, name this city whose remains have largely vanished because, in AD 330, its location on the Golden Horn was selected as his namesake city and capital by Constantine the Great.
This city, which may have been founded in the early 7th century BC as a colony of Megara, was besieged by Septimius Severus in AD 193.  
Byzantium (prompt on "Constantinople" or "Istanbul")