More commonly known as The Light Tower of the Sea, it is literally a sturdily built light house, built on a tiny rocky island, barely larger than the base of the tower.
If investigated, the weatherbeaten tower seems abandoned. There is carved graffitti on the walls going back quite a while. The lighting mechanism is a marvel. It’s clockwork mechanism runs seemingly without supervision and without visible means of power (perhaps solar or wind or magic). There is an odd whistling noise on the first floor, centered upon a good sized grate. There are signs that people have occupied here, nobody is here now.
If searched seriously enough, one can find a hidden lift. This will take one down, down into The Bastion.
The Dwarves have always been a pragmatic bunch. They realize that they are constantly underseige by Orcs, Elves, other mythics, and even their human friends. They needed a place to ensure that True Dwarves do surivive. So they found a place that was the most inhospitiable: in the deep ocean. (Well to the Dwarven point of view). There a Bastion would be built, so there would always be a Dwarven City to come back from.
The Lift drops one down into the sea mount. Into this mount, the Dwarves have built dozens of Holds (dwarven Towns). Building into the seamount has posed many challanges to the Dwarves, but it also provided many solutions. With ingenuity and inventivness, all the challanges were overcome. Dwarves were brought here secretly via magics gateways. Communities thrived here, in isolation.
These holdings have a great deal of clockwork magics. These devices keep supplying heat, air, and other goods to the space. There are miles of tunnels between the various Holdings and work places away from the holdings.
Choose the option that best serves your campaign
1) The Dwarves are still alive here. There is a somewhat thriving community here. There are deep conflicts between various clans in The Bastion. Without external enemies to fight, the Dwarves have looked to each other. Political manuvering and occasionaly open clashes between Holdings are the order of the day.
Oh by the way, you know they are here. You can not leave.
2) The Dwarves are alive here, but not where you are from. The Dwarven nightmare occured and they have been wiped out in the world. They only exist in The Bastion.
The Dwarves might have a grudge against you because your people eliminated their relatives. You may be kept alive for a while, just to find out what the world is like.
3) The Bastion is erriely empty. There some signs of a struggle, but there is enough dust and decay that they are masked. You might find some odd bones here and there, but it looked like the Dwarves just upped and left one day, in the middle of their soup.
a) They killed each other off. Old resentments simmered and exploded.
b) A plague creating zombie like Dwarves swept throught The Bastion.
c) Demonic monsters have taken out the cities.
d) The Dwarves simplied died out due to bordom.