What are the propeller-like looking things on the sides of the buildings?

Question

I saw them pointing all different directions on most of the buildings. Do they run off water, prevent flooding? They were flat, there would be several of them on one building, and they seemed to point towards windows.

Answer 1

Hallucinations.

Answer 2

i think they r called flying butresses...used to support the building...especially if it's an old structure.

Answer 3

They are a kind of small " iron joist" used as a reinforcement to the oldest building but they have nothing to do with water or flooding. They have been put there just to improve the stability of the ancient buildings and prevent the cracks on the walls.

Sometimes to check the stability of the buikding a small glass is inserted in the joist and if it brakes it means the walls are moving.