Detailed maps of Legend of Grimrock

Level 1 - Into the Dark

Level 2 - Old Tunnels

Level 3 - Pillars of Light

Level 4 - Archives

Level 5 - Hallways

Level 6 - Trapped

Level 7 - Ancient Chambers

Level 8 - The Vault

Level 9 - Goromorg Temple I

Level 10 - Goromorg Temple II

Level 11 - The Tomb

Level 12 - The Prison

Level 13 - The Cemetery

You should be able to get what the symbols mean by yourself. The green dots are Monsters I had not yet killed in my playthrough or Monsters that respawned.

The maps themselfs I screenshotted while having developer mode enabled.

Thank a lot to Punchy on the official Forums who told the world how to exactly do that in the first place.