Originally just a small Greek colony, Constantinople was built on a magnificent strategic sit on the wetern bank of the Bosphorus, that narrow sea-channel which separates Europe from Asia. Under Constantine, and especially under his Roman successors, it became the capitol of the eastern Roman Empire and at times of all Christian Europe. For more than ten centuries it was the impregnable bastion against which the eastern hordes of Islam battered in vain. It developed the rich civilization which we call Byzantine and which astonished western visitors by its magnificence. It was sacked by the Crusaders when on their way to Palestine in 1204. It fell to the Turks in 1453 and has since been a Moslem city, renamed Istanbul though with a Christian minority. The Patriarch of the Greek Church lived there.