From the glowing lava flows of Hawaii to the pearly ice fields of Alaska, the United States’ natural and cultural heritage is as vast and diverse as the country itself. The U.S. currently claims 23 UNESCO World Heritage sites, which capture thousands of years of natural history and human innovation. An additional 20 natural and cultural sites ranging from under-the-sea monuments to urban architectural wonders are also vying for the renowned title. Find out which sites have already been inscribed for their “outstanding universal value,” and which tentative sites may join the list soon.