The castle one can see at the far end of the Peninsula "Tir Geal" is located on the region "Hatmandor" of the Ignis Fatuus Grid.
The main object on "Hatmandor" is that dark castle build in the style of a half timbered building. A large stairway leads to the portal of the castle with two swords guarding the steps at the beginning. The portal itself is not on ground level but build fairly in the middle height of the building.
The skeleton guard at the side is harmlessly. Before I started to climb the stairs to get into the building I investigated on the surroundings of the castle but there is nothing of real interest. Just rock ground and a few dead trees.
Inside the castle there is not much. Four walk ways meet in the middle. The walks lead to openings aside from where you have a view over the area. Being inside the building you acknowledge that it is not a castle as it has the look from outside but a combination of towers, with the tallest in the middle. On the entrance level you will find a teleporter to the top of the middle tower.
And even an intensive search could not reveal any secrets at "Hatmandor". A bit disappointed I left this region to "Valtheim". Oh, I almost forgot to mention the interesting air vehicle turning its round at the border between "Hatmandor" and "Valtheim".
Ignis Fatuus Region Hatmandor