First, I started with the basic layout, I even used a ruler. This does have perspective and a vanishing point, sort of. I eyeballed it, and mostly just tried to keep it somewhat symmetrical.
Next, I colored the walls black, and added a second story of windows so it wouldn’t be too dark and imposing.
I added color! I used to use these prismacolor markers all the time, and I had fun playing with them again.
Finished! Used a fine pen to make any edges nice and crisp, and to darken the design of the rose window.