The tallest building in the world is the Burj Khalifa in Dubai, but the United States boasts plenty of vertical treasures worth marveling at — especially on Skyscraper Day, Sept. 3. It marks the birthday of architect Louis Sullivan, whose work in the 1890s helped make today's structures possible. Here are the 25 tallest buildings in America, according to information from the nonprofit Council on Tall Buildings and Urban Habitat and other sources. Some of the buildings feature viewing decks, which can have pricey admission fees, but there are deals and budget-friendly tips to alleviate them. And skyscrapers, like other architectural gems, may inspire even more awe from street level.