How do I add objects onto a curved surface?

This is the image I am trying to recreate.
However I am stuck on one part.
One side of the house is separated from the other by a curved wall rather than a corner.
How would i go about adding the shape I wish to the curved surface without it looking untidy.
For example if I made the window and tried to manually curve it, I doubt it would look very good so is there a tool that allows me to do what I mentioned?

This might help you. You should especially check the sections about the ‘spin’ and ‘to sphere’ functions.

Another approach would be to start by making the corner, and then extrude the walls.

i think you should do this work on corel draw.because that is use for these type of designing

well you could retopo a rectangle onto a cylinder

that would give the desired shape

hope ithelps

You can also use the warp tool to curve something. (At the bottom of the page Morio posted).

In the example photo, I do not believe that the windows are curved. It is an illusion from having the surfaces above and below the windows curved. To me, it appears that the window frames are planar.

I agree with jrboddie1. Windows are usually flat objects, especially in old-style buildings. I would model a single flat window frame and use an array modifier with a rotated empty to place the window frames on a circle.