Smithsonian National Museum of Natural History

Carved horses and an accessible chariot for riders who can't climb on, right between the museums.

The founding documents themselves, with interactive displays that explain them. The line can run long, so go early.

Wonderplace for small kids and Spark Lab for young inventors. Check the play areas are open before you go.

Galleries inside and a sculpture garden outside, so when kids are done with paintings there is room to walk among the big pieces.

Landmark planes and spacecraft overhead, and a gallery on how flight works with a plane kids can sit in. Book the timed passes first.

Holocaust history told through one boy's life, made for kids eight and up. Plan to talk it through with them afterwards.