Swim in a pond

I would love to have spiral stairs and curved stairs that can be used to make stairwells around the edges of circular rooms like those inside towers or lighthouses. It would be lovely to be able to make grand sweeping staircases for ballrooms, castles or celebrity homes etc.  

re swimming in the pond, I also have used the terrain tools and moo cheat to make a pool that looks more like a pond and in one instance it was almost completely surrounded by a pond so that it looked like a fishing pond that was swimmable and had a diving platform disguised by some rocks and plants.