Istanbul was known as the city on the seven hills. Whether Constantine the Great was actually aware of the fact that the new city was, founded on seven hills remains uncertain.
The seven hills, all located in the area within the walls, first appeared when the valleys of the Golden Horn and the Bosphorus were opened up during the Secondary and Tertiary periods. In the Ottoman, as in the earlier Byzantine period, each hill was surmounted by monumental religious buildings.
The first hill on which the ancient city of Byzantium was founded, begins from Seraglio Point and extends over the whole area containing Hagia Sophia, the Sultan Ahmet Mosque and Topkapi Palace.
On the second hill are to be found the Nuruosmaniye Mosque, Grand Bazaar and cemberlitas. The second hill is divided from the first by a fairly deep valley running from Babiali on the east Eminonu.
The third hill is now occupied by the main buildings of Istanbul University, the Mosque of Beyazit to the south and the Mosque and Complex of Suleymaniye to the north. The southern slopes of the hill descend to Kumkapi and Langa.
The fourth hill on which stood the Church of the Holy Aposties and, subsequently, the Mosque of Mehmet the Conqueror, slopes down rather steeply to the Golden Horn on the north and, rather more gently, to Aksaray on the south.
On the fifth hill we find the Mosque of Sultan Selim. The fifth and the sixth hills are separated by the valley running down on the west to Balat on the shore of the Golden Horn.
On the sixth hill are to be found the districts of Edirnekapi and Ayvansaray Its gentle slopes run out beyond the line of the defense walls.
The seventh hill extends from Aksaray to the city defense walls and the Marmara. It is a broad hill with three summits producing a triangle with apices at Topkapi, Aksaray, and Yedikule.