Maryland's biggest attractions by way of sightseeing are almost all in Baltimore, centered around the Inner Harbor, including the National Aquarium, historic Fort McHenry, the Maryland Zoo, and a host of great museums. Annapolis is sightseeing destination #2, home to the Maryland State House which once served as the nation's capitol, the U.S. Naval Academy, and a lovely historic center. Ocean City has its fair share of fun tourist kitsch as well. For more off-the-beaten path sights, look for the National Mormon Temple in Kensington at Christmas time, or visit Cumberland's historic district, set in the beautiful Allegheny Mountains.
