I took him to the art institute and we were stuck in the "China" room for 20 min. because he wanted to read all the informational signage. The china room was full of old dishes. That was what was fascinating. After a while I asked if we could move on to a different room. I'll have to dig around and see what I can find, but most programs that would be up to his ability level would have age limits and he wouldn't be in the limit.
I don't mind taking him to museums, historic sites, etc. We're going to Boston next summer and I'm going to put a lot of historic stuff on the itinerary. I just feel like he is quickly losing me, I'm not quite up to his level of fascination, and he has no peers.