One Place Baltimore, MD - Fort McHenry

Baltimore is a place I actually lived, Kendra and I were married there.  So there are a lot of places I'd like to visit. But if someone were visiting the city and there was only one place they could go - I would say Fort McHenry.  Even if some folks think it is unsingable - the words to our national anthem were written by Francis Scott Key as he watched the flag of Fort McHenry during a battle of the War of 1812. 
Not only is the history of the fort interesting - but even if it's only an historical monument - it gives Baltimore a different feel than most modern cities. The idea that the city is defended from outside attack makes the harbor feel more intimate and calm.  Of course most of Baltimore's present dangers are internal - we know that should some unnamed country attempt to take the city it would be well defended.

Websites: National Park Service.

Image: 

Fort McHenry with the city in background (from wheretraveler.com)

Video:

Smithsonian Channel video on Fort McHenry from Francis Scott Key's perspective.