The Smithsonian Castle is the red sandstone landmark that gave the Smithsonian its first permanent home. Today it serves as an introduction to the Smithsonian system, with information on the museums and occasional exhibitions inside.
Even a short stop is worthwhile for the building and its setting. Behind it, the Haupt Garden is one of the calmer places on the National Mall, with formal planting, shaded corners, and space to pause between museum visits.