Yellowstone – America and the world’s first National Park. With hot springs, steaming pool geysers, a canyon, a lake, and incredible wildlife, this UNESCO World Heritage site is centered over Caldera, the largest dormant volcano. While the area was inhabited by Native American’s centuries ago, it only became popular in 1871. The actual area of the park is estimated to be approximately 3472 square miles, so researching the areas you want to explore is key.