Hi Sanravi,
In Baltimore I can only think of the National aquarium. The aquarium itself will take a day plus travel. Here is the link
www.aqua.org
In and around D.C there is a lot to see. Depends on your interest, to name a few white house,capitol hill, Lincoln memorial, Washington monument and of course a dozen museums. I will give you the link so you can decide.
http://www.thedistrict.com/
Hope this gives you some idea.
Bye,