A view of the Gateway to the West from the St Louis Arch in the fog

Known as Gateway Arch or Gateway to the West, the Gateway Arch or Gateway to the West is a monumental arch that forms the centerpiece of the Jefferson National Expansion Memorial in St. Louis, Missouri, and it can be seen all across the city. This monument was built in order to commemorate the westward expansion of the United States of America. 630 feet (192 m) tall, it is the tallest man-made monument in the United States; it is the tallest accessible building in Missouri; and it is one of the largest architectural structures designed as a weighted or flattened catenary arch.

As the name suggests, the arch stands at the site of Saint Louis' foundation,[6] on the west bank of the Mississippi River where Pierre Laclède, just after noon on February 14, 1764, told his aide, Auguste Chouteau, to build a city