One of our best bunny purchases was their "fun house". Here is a picture of it with one of the castle towers on top of the fun house. Bunya and Ethel are snuggled inside. In winter, they go up there to enjoy the morning sunbeam that comes through the window.
Here is a post about the fun house: The bunnies' new BUNNY THING!!! It has more pictures in case you want to try to build one. Ours was a one-time project/fundraiser that we purchased from GHRS (lucky, because I have no such skills).
Well, the top was off the funhouse while we were cleaning, so here's Ethel playing around in the digging box portion (~40 sec).
[When I look at the published post, I cannot see the video.
I have reported this to Google.]