I just put a rectangular building and then rounded its roof as much as possible. After that, you must draw a path around each side to make a hollow volume. You can adjust the arch height once it's hollow.

So awesome. How did you make the arches with the roofs at the entrances?

indeed it is, a kind of interpretation of hagia sophia :)

Amazing!

Looks like Hagia Sophia before Ottoman Turk's modification :)

Beautiful