I'm not sure I ever named the castle on top of Felltower. Its history isn't really that old in the game, though - it's not the first fortress to be build on top of the nameless mountain north of Stericksburg.
It's only Felltower because the name is cool and then the PCs went and knocked down the only fully intact tower right away.
It has been a lot more important than I thought it would. I selected a ruined castle map from a Judges' Guild supplement I got from a website selling them right around when I first started this blog and got set to play GURPS Dungeon Fantasy. I kind of expected it to fade into the background faster than the terrain between the caves in the Caves of Chaos - there, but you get right on into the tunnels after session one.
It's current state is pretty interesting to me.
- it used to have a thick door and a portcullis that could be raised or lowered. The door was destroyed (I actually can't find which session or between which sessions that happened) and the gate locked down and the mechanism destroyed for looting purposes. The main gate is thus blocked. It can be knocked down, but it'll take some time (it's a heavy portcullis shielded against magic).
- the manor house inside once included a tower with a ghost. The tower was destroyed and the ghost ordered away.
- the manor house's partial roof was once patched up with canvas and hides by the orcs, but it was burned by the PCs in an attempt to discourage the orcs.
- its dry well turned out to be an opening into the dungeon (and thus clearly never an actual water well) but that was broken by the PCs and then the orcs blocked it off.
- the side walls were once crumbling, and usable as an entrance through the walls. The orcs fixed those with rubble-and-wood filled wooden fencing; subsequently someone finished them with magical and/or non-magical shaping.
- one tower held a collection of magical and non-magical treasures stashed by an adventuring group that the PCs looted.
- one tower held some giant maned rats but the PCs didn't explore that tower until long after the orcs claimed the surface and exterminated the rats.
- one gatehouse held the evidence of a previous fight - melted metal and coins and scorch marks of a large fire spell. (My group being my group, they looted the melted metal for scrap.)
As I noted in the Felltower Entrances rundown, the castle is pretty much accessed right now with spells and climbing.
Against my expectations, the castle is still really significant. It's an obstacle to entrance, a potential fortress against delvers, and still sometimes holds encounters. I'm glad I put enough thought in it to make it potentially so. I suppose in the right kind of game, the PCs would take it over, rehabilitate it, and live in it and adventure in their basement. I think my gamers rightly fear what happens in games I run to people who do that kind of stuff - they become backstory the next group of adventurers learns about the dungeon.