The ruins are in the middle of the swamp north of Cove and Lock Lake. In order to access it, you should walk counterclockwise around the swamp. A bunch of wooden planks marks the beginning of a path made of more wooden planks and small patches of solid ground.
In the ruins, as soon as you pick up any item, all the skeletons will come back to life.
On the map, it looks like the south-east portion of Dungeon Wrong, but if you are on foot, you will have to take a very long detour, following a river and countouring the swamp of Stonegate. The entrance to this dungeon is north-west from the wooden planks that mark the start of the swamp path.
