Workmen close the gap as they insert a 10-ton keystone, completing the 
Gateway Arch construction.

The Gateway Arch is a 630-foot monument in St. Louis, Missouri. It is the tallest
man-made monument in the United States and world. Built as a monument to the westward expansion of the United States, it has become an internationally known 
symbol of St. Louis.

Construction began on February 12, 1963 at a cost of $13 million. The monument
opened to the public on June 10, 1967.

The arch under construction, June 17, 1964