As a history teacher, you're probably going to want to do all of the following:

1. The entire damn Freedom Trail. Over, like, multiple days so you can spend adequate time at sites along the way. The Old State House, the site of the Boston Massacre, Paul Revere's House, the USS Constitution, Bunker Hill Monument, etc etc etc.

2. The annual reenactments of the Battle of Lexington and Concord.

3. Plimoth Plantation. 17th century.

4. Old Sturbridge Village. 18th century.

We also have a ton of museums and historical sites, depending on your specific historical interests. For instance, if you have an interest in the great age of whaling, you'll want to check out the Peabody Essex Museum in Salem. If you're interested in the industrial revolution, you'll want to check out the Charles River Museum of Industry and Innovation. If you're interested in military history, you might want to check out some of the historical forts that are still around. If you're interested in early American domestic architecture, you might head up to Strawbery Banke in Portsmouth, NH; if you're interested in maritime history, you might head down to Mystic Seaport in Mystic, CT.