I am living in a brick house built in 1925. We are planning to replace some windows.?

I notice that with most of the windows the wall forms an ';arc'; on top of the windows. However the windows itself is square. Some aluminum fills the arc between the window and the wall. Does this means that the windows originally had an arc and were replaced later with square ones ? or were they square from the beginning ?I am living in a brick house built in 1925. We are planning to replace some windows.?
It very much sounds to me as you suspect, that the windows once were arc shaped. It could be, that for cost reasons they were just replaced with simple rectangular windows.





One clue is to check similar houses in the neighborhood, and what windows they have. Any plans of the house or info in your town office? Another idea is to get a clue about the age of the existing windows. Windows from 1925 would be single glass with wooden frame.