This monument to the country's westward expansion is also an engineering marvel, which St. Louisans remain proud of more than 50 years after its construction. The stainless steel Gateway Arch, which was designed and submitted by Eero Saarinen during a national competition, rises 630 feet into the air and spans 630 feet from leg to leg. Visitors can learn more about the history of the arch at the Museum of Westward Expansion and the Gateway Arch Visitors Center. Opened in July 2018, the building sits below the arch and includes six new galleries that detail the history of the West. What's more, the park now boasts more than 5 miles of walking and biking paths.