I read that SF short twenty or thirty years ago.
A man is walking across land scattered with the remnants of human civilisation (broken crockery, etc.) He comes to an apparently deserted town and then finds a cafe with what appears to be a waitress gazing out the window. On entering, he finds the back of the cafe - and all the adjacent buildings - are merely their facades.The waitress isn't real and is standing on a ledge. Below this is a huge pit with the ends of cables and pipes protruding into it. He climbs down. That's all I can remember, except I'm sure aliens were involved.