A large dungeon below the island Fibula. You will find Dragons and Dragon Lords in the Deeper Fibula Quest area, while lower levels can hunt in the upper area. The entrance to the dungeon is located in the well (here) in the city of Fibula. In the well you might encounter a few Poison Spiders before you get to a door which may require a key depending on the last person to enter.
When you go into the dungeon and down the stairs, there will be several doors. Be careful, because there may be lured Bonelords or Demon Skeletons at the stairs.
To the east is "treasure" which is actually an empty chest (this leads to a room with 2 teleporters, one leads to the Deeper Fibula Quest area, one leads to the exit),
To the north is an area full of orcs (nothing else)
To the west is a a very large area that is good for lower levels to hunt in. It is mostly inhabited by rotworms but used to be inhabited by a Demon Skeleton which was removed in the 7.8 update and replaced with many Carrion Worms.
There is nothing to the south-west (you will be teleported here if you go through the teleport in the "treasure" area.