We took the MARC's Penn Line from Aberdeen to Washington D.C.'s Union Station, and then traveled by MetroRail to the Smithsonian Station, which exited at the National Mall. It was my first time travelling by train, and it was surprisingly easy. I was scared at first, but luckily, all of my preparation paid off.
We walked around the National Mall, then the Tidal Basin for cherry blossom pictures. Finally, we visited the Holocaust Museum. That was especially cool, because before you enter the exhibit, you get an identification card for a real person from the Holocaust. Each page corresponds to a different time frame/floor of the Holocaust/museum, and in the end you learn if they lived or died. It really personalizes the experience.
Here are some attempts at selfies from the trip:
I tried to get more of the building in with the Jefferson Memorial, but Chy jumped in, so...