
You can hoof it in DC, MoCo, PG County, and NoVA pretty decently due to the Metro. Baltimore, unfortunately, doesn't have comprehensive mass transit like DC, NYC, or Boston do. Most of the city is serviced by an inadequate bus system. There is light rail, but it mostly connects Owings Mills and Timonium to Downtown, with a couple of stops in Glen Burnie. It does connect to Penn Station and the Acela line that services the BosWash corridor.
When I lived there, I was as stranded without a car there as I would be in Phoenix. And that's a shame, because the city really needs something more than a bus that comes by every few hours to service a lot of its poorer neighborhoods.
There is definitley lots of interesting stuff there. One of my favorite places there was Boring, home of the Boring Volunteer Fire Department and the Boring United Methodist Church. It's northwest of Baltimore.