Does anyone have any suggestions for someone with 12 year old visiting National Harbor?

I'm looking for things to do this upcoming week in and around National Harbor. This includes Washington DC, also could be anywhere within approximately 30 minute drive from National Harbor.

It will be my nephews first time, he's not all that into history. Smithsonian seems like a possibility, but there's so many choices.

Edit: I'm well aware that National Harbor is in MD, folks. I'm just asking for suggestions of places to visit when I'm nearby DC(relatively). C'mon folks