The Ruined Castle Ravenloft

The original purpose of the castle was to house one of the Tridomatry's barons, as well as his family and servants. However, when the baron was overthrown by a small group of Vel To'ori members, it was repurposed as a shelter for refugees from Tridomatric raids.

The main alterations that were made with the Vel To'ori conquered the castle were to tear down the Tridomatric banners and replace them with Vel To'ori banners. Beyond that, the building's architecture itself was left intact.

Castle Ravenloft in its time was a sizable castle, built meticulously out of white bricks and decorated with red and gold banners. There were once buildings within the walls of the castle, mainly housing for servants and stablehands. These were built out of wood, though some of the buildings had stone frames.
There are no walls outside of the castle itself, but it's possible that this was because this castle was only for a minor baron instead of a more powerful or significant ruler.

Castle Ravenloft was known to the Tridomatrics by another name which has been lost to time. However, it's believed that the castle originally belonged to a minor baron who attempted to make everyone in his barony convert to Tridomatry. This is what's believed to have caused the rebellion against him, making it possibly one of the first rebellions to come under the blanket of The Great Rebellion.
After it had been conquered by the Vel To'ori, the castle became a safe place for its members to hide out in if they were attacked by the Tridomatrics. Over time it gained a reputation for being a popular place for refugees of Tridomatric raids.
Unfortunately, this was not to last forever. During the Great Rebellion, Castle Ravenloft was destroyed, with many of its residents being forced to evacuate. All that's left of it are segments of its walls and some of the torn banners.