Where you gonna be staying? There is Fort McHenry, if it is opened back up, you know, birthplace of the National Anthem. The inner harbor don't wonder too far away from it, last time I've been there has been quite awhile ago so I don't know if it has changed a lot. Edgar Allen Poe house, Baltimore and Ohio Railroad Museum if you are into trains, S.S. John W. Brown if your into WWll ships, Babe Ruth Birthplace and Museum, Baltimore Civil War Museum, Flag House. There should be pamphlets where you are staying, you could probably get info from locals where you are staying or working.
Heck you could walk past where my GP's lived many years ago around the inner harbor and Locust Point.
Don't take a firearm with you MD isn't a gun friendly state for CCW that's why I moved years ago.