National Parks
I've visited a handful of other National Park Service locations that aren't designated parks, but rather monuments, or historical sites, or etc ... They're worth noting, as well.
  1. Antietam National Battlefield (Maryland)
  2. Abraham Lincoln Birthplace National Historical Site (Kentucky)
  3. Bandelier National Monument (New Mexico)
  4. Blue Ridge Parkway (North Carolina)
  5. Canaveral National Seashore (Florida)
  6. Cape Cod National Seashore (Massachusetts)
  7. Castillo de San Marcos National Monument (Florida)
  8. Cowpens National Battlefield (South Carolina)
  9. Ford's Theatre National Historical Site (District of Columbia)
  10. Fort Matanzas National Monument (Florida)
  11. Franklin Delano Roosevelt Memorial (District of Columbia)
  12. Fort McHenry National Monument (Maryland)
  13. Fort Sumter National Monument (South Carolina)
  14. Gettysburg National Military Park (Pennsylvania)
  15. Golden Gate National Recreation Area (California) Alcatraz
  16. Harpers Ferry National Historical Park (Maryland, Virginia, West Virginia)
  17. Indiana Dunes National Lakeshore (Indiana)
  18. Kaloko-Honokohau National Historical Park (Hawaii)
  19. Korean War Veterans Memorial (District of Columbia)
  20. Lincoln Boyhood National Memorial (Indiana)
  21. Lincoln Memorial (District of Columbia)
  22. Manhattan Project National Historical Park (New Mexico)
  23. Mississippi National River Recreation Area (Minnesota)
  24. Mount Rushmore National Memorial (South Dakota)
  25. National Mall (District of Columbia)
  26. Old Post Office Tower (District of Columbia)
  27. Petroglyph National Monument (New Mexico)
  28. Pinnacles National Monument (California)
  29. Pu'uhonua o Honaunau National Historical Park (Hawaii)
  30. Santa Monica Mountains National Recreation Area (California)
  31. Sleeping Bear Dunes National Lakeshore (Michigan)
  32. Thomas Jefferson Memorial (District of Columbia)
  33. Valley Forge National Historical Park (Pennsylvania)
  34. Vietnam Veterans Memorial (District of Columbia)
  35. Washington Monument (Pennsylvania)
  36. White Sands National Monument (New Mexico)