Sorry to bother and nitpick. But from your picture, it looks like a single building with parts of different heights (looking at the kindergarten and the balcony on the left side). If it's right, I would rather use building:parts It doesn't matter much I guess, but in my project to list cooperative (https://github.com/imagoiq/swiss-housing-cooperative-map), it changes the count of buildings. It's something I had to think about as from the architecture point of view the count might be different than how we map it.