In 330 CE the Roman emperor Constantine refounded the Greek city of Byzantium as Constantinople, his new imperial capital on a defensible triangular peninsula commanding the Bosporus. The rebuilt city was laid out with imperial fora, a great colonnaded ceremonial avenue (the Mese) as its spine, a hippodrome, palaces and churches, and was later ringed by the formidable Theodosian land walls. Its position controlled the trade route between the Mediterranean and the Black Sea and between Europe and Asia. It was conceived as a self-consciously Christian and Roman capital.
It set the template for the planned Christian imperial capital and served as the seat of the Byzantine Empire for over a thousand years. Its monumental armature and great walls influenced city-building and defensive design across the medieval world.