National Archives

A treasure trove of the United States' founding documents, the National Archives are high on the list of travelers' to-do lists and almost always have long lines to get in. But once you do get inside, you'll see the Declaration of Independence, the Constitution and the Bill of Rights, along with one of the surviving copies of the Magna Carta and the Emancipation Proclamation. Other exhibits, some of which experts say are interactive and kid-friendly, fill the museum, which is located off the Archives/Navy Memorial metro station.

Though the museum is open daily, booking a reservation (about six weeks in advance) to visit is strongly recommended.