Click on the Arch symbols throughout the site to see facts about St. Louis' iconic monument.

You can scroll around some images to see more.

The Arch is an inverted catenary curve. (Picture the curve that forms if you hold a free-hanging chain at both ends.)

In February 1764, Auguste Chouteau and his party of French settlers began laying out the streets of colonial St. Louis. By the end of the Civil War in 1865, the city's population had grown to 160,000.

During the first half of the 19th century, the St. Louis levee bustled with steamboats and pioneers heading westward. But with the completion of the Eads Bridge in 1874, trains were able to cross the Mississippi.

As river traffic declined, so did business along the levee. By the end of the 19th century, civic leaders began to float plans to revive the riverfront.

The project won the financial backing of the administration of President Franklin Roosevelt, and in September 1935 St. Louis residents approved a contentious $7.5 million bond issue to fund the city’s share of the project. The city was in the throes of the Great Depression, and supporters argued that the project would provide jobs. Opponents decried the tearing down of nearly 40 blocks of homes and businesses through eminent domain.

Demolition began on June 30, 1939 and was completed in May 1942. Business owners and residents, many of them African American, were displaced, and some of the city’s oldest historic buildings were razed. The project then stalled for years – first by World War II and then by a lack of funding. The emptied ground was used as a parking lot.

The Arch project spanned three decades and five presidencies: Franklin Roosevelt, Harry Truman, Dwight Eisenhower, John F. Kennedy and Lyndon B. Johnson.

It’s comprised of 142 stainless steel sections shaped like equilateral triangles that decrease in size, from 54 feet at the base to 17 feet at the very top.

Concrete was poured into the space between the skins to about 300 feet, which is about half way up the legs of the Gateway Arch.

Insurance estimates had predicted that 13 workers would be killed during construction, but there were no fatalities.

630 feet: the height of the Arch and also the distance between the structure’s north and south legs, at ground level.

It’s the tallest monument in the U.S -- 75 feet taller than the 555-foot Washington Monument in the nation’s capital.

The Arch is taller -- and younger -- than Seattle’s Space Needle, which was completed in 1962 and tops out at 605 feet.

The Arch weighs an estimated 17,246 tons.

The signatures of 762,000 area schoolchildren and well-wishers were sealed into a time capsule welded into the final 8-foot section -- the keystone -- of the Arch.

Luther Ely Smith, a St. Louis lawyer, is credited with envisioning the national memorial as a way to revitalize the St. Louis riverfront. Mayor Bernard F. Dickmann appointed Smith to head a civic committee in December 1933 to get the ball rolling.

Both legs have trams: Eight-capsule transports that run up and down on tracks. The Arch’s unique tram system began operation in 1967.

Tram speed: 3.9 miles per hour. (It takes about 4 minutes to get to the top.)

The capsules rotate to keep passengers upright during the trip, similar to a Ferris wheel.

The viewing area at the top can hold about 150 people.

There are 32 windows (16 on each side).

The Arch was built to withstand high winds and earthquakes. It will sway about 1 inch in a 20 mph wind, and will sway up to 18 inches in 150 mph winds. (An EF-4 tornado packs winds of from 166 to 200 mph.)

On a clear day, you can see about 30 miles.

On Oct. 28, 1965 -- a Thursday morning -- thousands gathered on the riverfront to watch the final section of the Arch lifted into place. Helicopters buzzed about, and Vice President Hubert Humphrey watched from a helicopter.

When the keystone was being placed, city firefighters used 700 feet of hose to pump water onto the south leg at about the 550-foot mark to cool the steel and prevent it from expanding in the sun’s warmth.

When the Arch was completed, the ultra-modern Busch Stadium II -- with its bowl design and crown of 96 arches -- was also nearing completion.

The Arch is part of the Jefferson National Expansion Memorial. In addition to the 62-acre Arch grounds, the memorial includes the Old Courthouse and Luther Ely Smith Square.

The Arch was designed by architect Eero Saarinen who won a competition held in 1947 for a riverfront memorial. The competition drew 172 entries from unknowns and big names, like Walter Gropius and Charles and Ray Eames.

Original projections in the 1930s estimated that the memorial would cost about $30 million, including development, land purchase and construction. The actual figure was about $51 million.

For the reconstruction, the landscape architecture firm – Michael Van Valkenburgh Associates – was chosen through an international design competition held in 2009.

CityArchRiver 2015, a public-private partnership, is funding and coordinating the $380 million project. The Funding breakdown: $69 million in public money from federal, state and local sources, $90 million from Proposition P, approved by St. Louis city and county voters in 2013; $221 million in private funding – gifts, grants and donations -- raised by the CityArchRiver 2015 Foundation.