Byzantine City Walls
Address: All around the city
Constantinople's great city walls were breached only twice in 1600 years.
The 5th-century city walls built by Emperor Theodosius II stretch for 6.5 km (4 miles) from Istanbul's Golden Horn to the Sea of Marmara.
It can be seen from many points in Istanbul, but it's easiest to combine a view of the walls with a visit to the Kariye Museum (Chora Church) and the nearby Byzantine Palace of Tekfur Saray (Palace of Constantine Porphyrogenetus) in the Edirnekapi (Edirne Gate) district.
Another good vantage point, relatively easy to reach, is Yedikule, the Fortress of the Seven Towers.