D20srd.org has an automatic random dungeon creator. It's rarely sensible but even a rogue needs exceptional luck and several levels to make the detect and disarm checks that it comes up with. The monsters it populates the dungeon with are appropriate to the level you set
It creates a player's map and a GM version
I thought the Celts walked to the British Isles while they were connected to Europe. Guess I need to improve my British prehistory