The Northern Tyrant [Game of Thrones] - Wylis' Solar in Ramsgate Castle (Patreon)

The solar was designed and maintained by Brennard. Commonly, the solar is like a study/office where the Lord does his official business, the Lord's private chamber. It was commonly an upper room, or the upper part of a medieval house. But since Brennard was merely a steward, he had no lordly business.

While Wylis has one of those official Solar in the tallest tower on the top floor, this one is more preferred because it's on the ground floor and easy to access. 

And Wylis loves it because he gets to spend time with those he cherishes while working on his plans.