The process of acquiring financing for the Gateway Arch began in the 1930s, while the nation was mired in the Great Depression. Though pitched as a New Deal-era program that would create much-needed jobs for the city, the project proved controversial—and costly. Building such a large structure required razing nearly 500 existing structures at the waterfront district site, spurring a slew of legal battles, says Sean Rost, assistant director of research at The State Historical Society of Missouri. Those lawsuits dragged on throughout the decade, says Rost, as did the slow process of gaining congressional approval and presidential sign-off.

In the 1940s, World War II further held up progress, delaying the design competition until 1947. In the following decade, the Korean War curtailed funding for the structure. After breaking ground in 1959 and beginning construction in 1963, the arch finally opened in October 1965, at a cost of close to $15 million.

In 1947, the Jefferson National Expansion Memorial Association announced its design competition for the monument. The committee received 172 ideas from architects and designers, including animal-shaped sculptures and a statue showcasing the signing of the Louisiana Purchase.

When the competition began, the front runner appeared to be Harris Armstrong, a local St. Louis architect whose submission resembled a “giant plow” moving into the levee, Rost says. But ultimately, after reviewing five finalists, the seven-person jury chose the bold, modernist design of Finnish-American architect Eero Saarinen. “Its size, its dynamics, its landscape is what wins it for Saarinen’s over Armstrong’s,” he says.

In a regrettable oops, the committee mistakenly telegrammed Saarinen’s architect father, Eliel, that he had won the $40,000 prize for his own submission of “a tall, rectangular stone gate.” It took three days for the error to be corrected.

In 1935, St. Louis residents voted on a $7.5 million bond issue, combined with federal money, to fund the project. This 1935 local election had a suspiciously high turnout and approval rate, with 123,299 votes (71 percent) in favor and 50,713 against.

According to the Arizona Daily Star, the St. Louis Post-Dispatch published a lengthy Pulitzer Prize-winning investigation in 1936, reporting “widespread fraud” in the election—including phony votes from residents who said they never casted ballots. A city grand jury’s request to examine ballot boxes was denied, and the lawsuits fizzled.

Clearing land for the arch required bulldozing nearly 40 square blocks of property along the waterfront, including 290 businesses, according to Smithsonian Magazine. Historic cast-iron buildings, which housed small factories where 5,000 workers held jobs, fell to the wrecking ball.

African American communities bore the brunt of displacement. But such efforts were typical in cities that wanted to replace what they considered “blighted” areas with highways and venues that would draw visitors, Tracy Campbell says.

“Of course, what it did was just destroy neighborhoods,” he adds.

No one had ever before built anything quite like the St. Louis Gateway Arch—and despite safety concerns, Campbell says, it’s a miracle nobody died during construction.

“Every single piece was different, smaller, curving, and you have to work inside these in the middle of summer in St. Louis, where the temperatures and the humidity can be pretty brutal,” Campbell says. Putting an elevator inside the curved stainless steel exterior was also unprecedented.

Absolute precision was a must. Some questioned whether workers would actually succeed in connecting the two legs at the top of the arch, since even the tiniest deviation could have led to an engineering fiasco. Plus, there were worries that drastic temperature changes in St. Louis could cause minute (yet impactful) shifts in the structure’s measurements, Rost says.

During construction, it became clear that work teams lacked racial diversity. On July 14, 1964, Black activist Percy Green, joined by white college student Richard Daly, climbed 125 feet up the scaffolding of the arch’s north leg in protest, just days after President Lyndon B. Johnson had signed the landmark Civil Rights Act of 1964.

“It was a poignant moment of saying, ‘If we’re going to pass such legislation, let’s also ensure our projects, our national landmarks, also are open and available to all—not only in their accessibility, but also in their construction as well,’” Rost says.

By 1966, the National Park Service altered its hiring practices and, the NPS says, employed an African American firm to help operate the site’s visitor center.

The vast height and striking design of the Gateway Arch has attracted thrill-seekers eager to perform attention-grabbing stunts off the structure—despite laws prohibiting them from doing so.

In 1980, Kenneth Swyers made a bold attempt to jump out of a plane and land on top of the arch. But his plan to then parachute to the ground was thwarted when his chute failed to open, and tragically, he slid down the north leg to his death. In 1992, base jumper John Vincent used suction cups to climb to the top of the arch, before parachuting off. He earned three months in federal prison for his feat.