Galata tower
Galata tower. This is the stair that goes around the tower. The tower was built by the Genoese as they were big traders. They actually took over a portion of the area in Istanbul under the Byzantium rulers. They had their own government and defense. I read today the ottomans built defensible Castle from which they attached the city. It reminds of age of empires where you could win by just building on your enemies land. I guess it really happened that way.
The chain across the harbor was to protect against ships going into the harbor and attacking the city. I had always wanted to see what the chain looks like. Here is the actual portion of the chain that was used.