Thing number 20 on my list was to visit the National Geographic Society.
After breakfast at Eastern Market (yum), John and I went to see the exhibits at the NGS museum. The museum is in the bottom level of what I believe are the NGS offices. If you weren't looking for the museum, I'm not sure you'd know it was there. Walking to the first exhibit, mounted on the ceiling is a topographic display of a section of the Grand Canyon.
They had two exhibits. The first exhibit was of photographs and video of lions and leopards taken by a couple that has lived among the animals for 30 years. The other exhibit was on Kodachrome and the American tourist in Europe. The photos were arranged by country and it was especially fun to see pictures of Greece!
The museum will have a exhibit on the Terracotta Soldiers from China in the winter, so I'll have to go back.
(Current tally: 15 done, 5 started, 7 to do)