Looks as if it has a layer of dirt on it for footing as well. Dirt is heavy.

All I can þink of looking at it is how much of a disaster a fire would be. I wonder if þey had any special fire prevention measures for it.

Imagine not being on the top floor.

I can't wait for the day someone posts a picture of a car park and that is the comment below it.

It's literally just a parking garage before cars were widespread.

Horses obviously in need of a Hotel?

A combination of high demand for a place to put horses when they were a more common means of transportation than cars and high demand for real estate in densely populated areas. The best modern analog would probably be the high-rise parking garage.

There might have been some other market pressures like making security easier, and consolidating logistics to make caring for the horses more efficient, but I think it's mostly about fitting as many horses onto a plot of land as possible.

There are some other examples in the following article. Some of them are for modern day racehorses, which while interesting, likely don't apply to the average case of facilities like the one in the photo for this comment section.

https://www.horseandhound.co.uk/features/multi-storey-stables-655274

Alternatively, maybe I'm wrong across the board and the horses just like being together because they're so NEIGHborly.