The Adams family sights are accessible by guided tours departing from the Adams National Historic Park Visitor Center. Every half-hour (until 3:15pm), trolleys travel to the John Adams and John Quincy Adams Birthplaces, the oldest presidential birthplaces in the USA. The half-hour film Enduring Legacy is also shown at the visitor center. Note that the admission fee is payable by credit card only.
The two 17th-century saltbox houses stand side by side along the old Coast Rd, which connected Plymouth to Boston. The houses are furnished as they would have been in the 18th century, so visitors can see where John Adams began his law career, started his family and wrote the Massachusetts Constitution (which was later used as the basis for the US Constitution).
From here, the trolley continues to the Old House, also called Peacefields, which was the residence of four generations of the Adams family from 1788 to 1927. The house contains original furnishings and decorations from the Adams family, including the chair in which John Adams died on July 4, 1826, the 50th anniversary of the Declaration of Independence (and, spookily, the same day that Thomas Jefferson died on his estate in Virginia). In the grounds, the spectacular two-story library and the lovely formal gardens are highlights.