I really the Pantheon in Rome.
Not a museum technically.
Built as a temple to the Gods by the Romans.
Converted to a Roman Catholic church.
It has great doors and the largest concrete dome in the world. Just barely 2000 years old. The concrete is still curing.
You reminded me of this; I bought it years ago and never put it together:
https://www.papermodelsheet.com/en/p/pantheon-rome