Help crack the Founding Father's codes at Mount Vernon. take a guided, behind-the-scenes tour to see the role that the estate played in "National Treasure: Book of Secrets," and how the locations were used during George Washington's time. Download the Mount Vernon App ahead of your visit so you can have access to on-board maps, information on over 100 points of interest, fun challenges and more. $$. Mount Vernon, VA. mountvernon.org

Walk through history at Antietam National Battlefield, which is the site of the first invasion by the Confederate Army to the North. Cruise through 8 1/2-mile driving tour or stretch your legs and hike through the battlefield. The two hour Highlight Tour is designed especially for those with young children. Entrance to the park is free for children under 15 years of age. Sharpsburg, MD. nps.gov/anti

Celebrate the legacy of Frederick Douglass at his home, Cedar Hill. Stop into the Visitor's Center to purchase house tour tickets, look at exhibits and watch the short film "Frederick Douglass: Fighter for Freedom." After the tour, explore the beautiful grounds while enjoying one of the best views of Washington, D.C. $$. nps.gov/frdo

Travel back in time at the Clara Barton Historic Site, the estate that Barton called home for the last 15 years of her life. In honor of the 150th anniversary of the Civil War, kids can even earn a special Clara Barton Junior Ranger Patch. Stop by the Irish Inn after your visit for some delicious pub food. Free. Glen Echo, MD. nps.gov/clba/index.htm

Relive Lincoln's presidency and assassination at Ford's Theatre. The new exhibit, "Lincoln and Leadership," allows visitors to explore Lincoln's legacy of good leadership and gives a deeper understanding as to why Lincoln has remained relevant today. After touring the theatre, head across the street to the Peterson House to learn more about where Lincoln spent his final moments. $$. Washington, D.C. fordstheatre.org

See the wild side of D.C. at Theodore Roosevelt Island. Look carefully and you'll spot some of the island's wildlife on a ranger-led "Island Safari" and "Birding with Teddy" tour. See if you can identify the many different kinds of birds native to the island, including raptors, wading birds and warblers. Encourage kids to keep track of the miles they hike with an online "Track Trails" journal. Free. Washington, D.C. nps.gov/this

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