The tallest monument in the United States is The Gateway Arch in St. Louis, Missouri

The Gateway Arch happens to be one of the newest monuments in the National Park system. It stands a record 630 feet (192 meters), making the Missouri monument the tallest in existence. The Statue of Unity in India is the second tallest at 597 feet (182 meters). By comparison, other well known landmarks like the Eiffel tower and Empire State Building are 984 feet (300 meters) and 443 feet (135 meters) respectively.