The United States Botanic Garden is hosting a holiday exhibit celebrating the 100th anniversary of the National Park Service and the 50th anniversary of the National Historic Preservation Act. In their model train show, the trains chug around, below, through and above re-creations of iconic national parks and sites in the National Register of Historic Places, all made from plants and other natural materials. The West Gallery houses a large indoor tree decorated with national park ornaments as well as a model of the Old Faithful Inn and geyser. In the Garden Court are models of landmarks from the nation’s capital, again all made from natural materials, along with more than 30 varieties of poinsettias featuring old and new forms and colors.

The Castle and headquarters of the Smithsonian Institution, made entirely from natural materials. All the models of Washington, D.C., historic landmarks appear as they were originally constructed (so many look quite different today, but the Castle is pretty close).

US Botanic Garden Conservatory, posted earlier: