My door mechanisms will be designed so that blasting the control panel on the outside seals the door and blasting the control panel on the inside opens the door, not vice versa.

My ventilation ducts will be too small to crawl through.

I will hire a team of board-certified architects and surveyors to examine my castle and inform me of any secret passages and abandoned tunnels that I might not know about.

I will design fortress hallways with no alcoves or protruding structural supports which intruders could use for cover in a firefight.