Arrows pointing on staircases always point upstairs direction.
What is this place now? That’s up to you, Dungeon Master! I can only tell you what it USED to be, so you can know how to dress the dungeon in the background.
The nobleman would enter by the stairs down from the secret door in his “personal study” behind a bookshelf, coming to the southwest corner. An inviting lounge area, often with furniture, for himself to get ready and for him to orient his guests when he brought them down.
To the left, down the stairs, his bedroom. The main event, as it were. A table for chatting, a dresser, a screen for dressing and undressing. Then, to the north, stairs leading down to the built-in hot tub.
To the right, from the entrance, the more public area. An impressive foyer with a huge statue of a couple, the noble and his woman–the woman statue having been retooled many times, as needed, to reflect a new face.
Southeast, down the stairs, to a room where the men-at-arms and non-essential servants of his guests would wait, in a chamber with colorful frescoes of scenes celebrating the noble’s family and their exploits. Then down further, to a rough room where boats could be pulled in and supplies stored. A statue of his patron god also (either Proteax, god of the sea and change, or Silamos, god of shadows and indirect balance-keeping action.) The tiny beach accesses the river, and is difficult to find if you don’t know exactly where it is.
To the north from the lounge, go to the theater. Whatever mistress the noble has at the moment, she must have some talent suitable for impressing his peers, and this stage is where she can showcase it for a select few that may witness the noble’s “private collection” style exhibitions of her gifts.
Behind that, her waiting room, designed to be unreachable by all save the noble when properly guarded.
Feel free to use and enjoy (and restock!) this recreational secret.