Hard to tell which one is the oldest. Day 2 in DC we went to the Smithsonian Museum of the Natural Sciences. Really enjoyed this but our backs and legs were giving out on us quickly after yesterdays walks. We left here and walked down the street to the National Art Institute. We had to leave early in order to beat the traffic and all the commuters boarding the Metro Subway going home from work. Will be back tomorrow and visit the Aeronautics and Space Museum.