According to the core rules, a keep costs 50,000gp to build from scratch. There's a piece of art in one of the official adventures that's 50k gp all by itself.
— Matthew Colville (@mattcolville) March 17, 2018
You can buy a castle in France for $12M. The Mona Lisa is valued at over $600M. https://t.co/2bm7ByJIv0
— Christopher Perkins (@ChrisPerkinsDnD) March 17, 2018