On Memorial Day, we honor those that have fallen in the service of our nation. You can take part by visiting Colonial era sites like George Rogers Clark National Historical Park in Indiana, a Civil War battlefield like Shiloh National Military Park in Tennessee or a memorial on the National Mall like the Vietnam Veterans Memorial in Washington, DC. These memorials, cemeteries and battlefields help remind us of the extraordinary sacrifices made to keep us united and free. Vietnam Veterans Memorial photo by Thomas Kredo (www.sharetheexperience.org). George Rogers Clark National Historical Park and Shiloh National Military Park photos by National Park Service.