Zámek Frýdlant

Where: Frýdlant, Czech Republic

Start of construction: 13th Century

reconstructions: 16th & 17th Century

Most important renovation: 19th Century

Accessible: yes, but only with guide

Important fact:

State owned since 1945.
Located 10 kilometers from the Polish border.

https://www.zamek-frydlant.cz/en