America's tallest man-made monument at 630 feet, the Gateway Arch has beckoned visitors for more than 50 years with its iconic, awe-inspiring shape. The vision of renowned architect Eero Saarinen, the Arch commemorates Thomas Jefferson and St.

The Gateway Arch in St. Louis, Missouri, holds the title of the tallest man-made monument in the United States, standing at 630 feet (192 meters) tall. However, if you define "largest" by volume or mass rather than just height, the Washington Monument in D.C. is a strong contender as the world's tallest stone obelisk (555 feet). In 2026, another "largest" monument often cited is the Mount Rushmore National Memorial, though it is a sculpture carved into a natural feature rather than a free-standing built structure. If considering unfinished monuments, the Crazy Horse Memorial in South Dakota will eventually be the largest in the world by volume once completed. For 2026 travelers, the Gateway Arch remains the most iconic "largest" structure specifically built as a monument, featuring a unique tram system that takes visitors to the top of its stainless steel catenary curve to view the Mississippi River and the city of St. Louis.