Here are the lines for the roof of the St. Peter’s Basilica map. It’s probably a little hard to parse what you’re looking at here, especially since this roof– very unusually– has a number of features that are recessed into the roof (as seen here, on the right). Plenty of roofs have things sticking out, but recesses are pretty rare, since they tend to fill up with water. I’m not sure how they avoided that here, but they seem to have worked something out.
Anyway, I’m gonna get to work on coloring this tomorrow. At the moment, I am incredibly sick and I’m going to give my disease-ridden body a day to rest. All right, I’m going to go lie down.