If you search the buildings list for "Vulcan," you will find a neat bench. I like to use this bench, but (since it's miscategorized as a building), there is a limit of like 35. Plus, each time I use it, it takes away from the total number of buildings I can use.
Seems like a simple mistake that could be a quick fix. If I recall, there are a few other non-buildings in the buildings list. Vases and statues, I think.