Hi Happy Color!
As Lisa stated, not sure if you were planning on just walking the freedom trail, or going inside any of the buildings.
Also, the Union Oyster House is a great restaurant! I've been there for dinner on non-cruise trips up to Boston, since my sister did her undergrad at BU.
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)