No, the buildings do not have interiors - but the 'Mean Sets' are meant to be 'movie set' interiors. They do not actually fit into the buildings, but you can cut scene to interiors from the action in the streets.
And yes, they are somewhat pricey, and you need foam board to back them. But I like them. And they're still cheaper than resin, plus you can easily repair any damage (if you buy the pdfs as I'm going to - Pat Wilson is converting them into a set of A4 on my demand, so I do not have to worry about them fitting on my printer

- nice for other non-US residents, too, I guess). The Twilight Street buildings are very nice too (as is Worldworks Games' Mayhem series), and I'm just being a cranky old lady about the timescape

Now you have me going - I really need to get home and print out a couple of TS/HS buildings and get them assembled tonight. Maybe some modelling will help me back on the painting track again, who knows...
