After touring the historic Washington monuments display and the NPS tribute, we (or more correctly, I) decided to also see the model train exhibit, which in reality was a series of re-creations of iconic national parks and sites in the National Register of Historic Places, all made from plants and other natural materials, with some model trains running through, around or above them. I must add that this exhibit was staged in a darkened gallery, and the lighting was in very unusual colors.

Cliff Dwellings, Mesa Verde National Park, in California

Mattes Street Signal Tower, posted earlier: