A cave with weapons sunken into the walls, blades sticking out of the floor and ceiling, and so on. Possibly, any weapon used in it could be torn out of the hand and sink into the stone.
“ All estates, manors, castles, fortresses, and palaces are required by the King's Law to be converted into civilian shelters in the event of national emergency such as a disaster or attack. This includes the Royal Palaces. It is an act of treason to fail to comply such an emergency order.”
“ A revolt or attack happens against a strong city/kingdom. All the losers of the battle that can be captured are brutally crucified along the roads that enter the kingdom to show their strength and as a demonstration of what happens to their enemies. ... a long road, decorated with hundreds of dying crucified soldiers... You see them bleeding, you hear them screaming and whispering for help. Do you really want to enter this reportedly peaceful kingdom?”