In the early 2000s Build A Room kits had reversible walls to make TWO rooms.
The lock in place floor design holds the slide in place walls for complete room set up. Similar to the Mi World sets sold today.
Reverses to reveal another room!
The furniture is sold separately. These will work well with any fashion doll and some of the furniture pieces can work with AG and OG minis.
You can find these sets on eBay.