What is the dungeon like?

a dark usually underground prison or vault

Explanation:

Dungeon was first used in English in the 14th century for the strong tower in the inner part of the castle. Defenders could retreat to this tower if attackers got inside the castle walls. Part of the tower usually included an underground room, the dungeon, usually used for prisoners. Throughout its history, the word dungeon has had many spellings. Sometimes it was spelled donjon like the French word it comes from, and sometimes in other ways. In time the spelling donjon came to be used mostly for the castle tower, and the spelling dungeon mostly for the underground room or prison.