It’s almost a law that if you visit St. Louis, you go to the Arch (or to be more official, “The Gateway Arch”). National Park monument, unmistakable city landmark and indelible symbolic icon, it’s a necessary sightseeing pilgrimage.

I made the pilgrimage on a steamy, hazy August Friday morning. The Arch stands overlooking the Mississippi River on the leafy grounds of the Jefferson National Expansion Memorial park. In downtown St. Louis the river is only about 12 to 15 feet deep and pokes along at a normal speed of 3 miles an hour, so all eyes instead turn to Finnish architect Eero Saarinen’s gleaming stainless steel structure. Architecturally speaking the design is called a catenary curve—the shape that a free-hanging chain takes when held at both ends. The geometric form is ingenious in its simplicity, even though the engineering mathematics are complex (start talking about hyperbolic cosine functions and you totally lose me).

As is the case with most things this famous, there are a host of fun facts about the Arch. Would you like to learn a few? I thought you would.
• It’s 630 feet tall. That’s also the span of the legs at ground level.
• It weighs 17,246 tons.
• It took about 2 years and 8 months to build.
• Both legs were constructed simultaneously, and the margin of error for the failure of each leg to align precisely so they would meet was 1/64 of an inch.
• The usual sway is half an inch, but the Arch would sway up to 18 inches—9 inches each way—in a 150 mph wind.

Of course none of this was on my mind as my friend and I stood in line at the north leg; I just wanted to get out of the heat. But it wasn’t long before we entered a big underground complex that had restrooms, a gift shop, the Museum of Westward Expansion and a theater where you can watch a film about explorers Lewis and Clark.

We took a quick spin through the museum while waiting to go to the top (your entry ticket includes a designated departure time). The exhibits chronicling Lewis and Clark’s great journey west to the mouth of the Columbia River are well done, with a couple of those slow-moving, speaking mannequins that look like wax museum figures come to life. But this was a sideshow to the main event, and when our time came to board the tram for the ride to the top I must confess to a little anticipatory excitement.

I have to explain this in some detail, because it wasn’t what I was expecting. In fact I’m not sure what I was expecting, but obviously the Arch’s shape precluded installing a standard elevator. We were herded to a flight of stairs, standing in front of the tram doors in groups of five. TV monitors overhead showed a short video about Eero Saarinen’s vision for the Arch. The doors to the tram cars opened and people exited. Then my group—all adults—shuffled into a cramped, egg-shaped pod with five seats and a low, sloping ceiling. After we awkwardly arranged ourselves so that our knees weren’t knocking together, the door clanged shut.

The trip to the top takes four minutes, but it seemed longer. It was warm. It was claustrophobic. It was silent. Finally a big, strapping man said, “Your mother would not like this,” to which his equally strapping son replied, “No sir, she wouldn’t.” That was the extent of the conversation. The door had a narrow window through which I caught glimpses of metal stairways, metal pulleys and unidentifiable, slightly ominous-looking machinery.

To pass the time I imagined that I was Sigourney Weaver in “Aliens,” taking that freight elevator from the rescue ship back down to the alien queen’s lair in order to rescue Newt—only I wasn’t packing heavy artillery and a flamethrower.  I also tried not to think about what would happen if for some reason the tram system malfunctioned. (This actually happened in 2007, when an electrical problem trapped visitors in the trams and at the top of the Arch for a short period.) Let’s just say I was happy to get out of that thing.

The small observation room has 32 narrow windows—16 on each side—and a slightly arched floor. The windows are only about two feet wide and less than a foot tall, which is why you can’t see them when you’re standing outside on the ground looking up. You also have to bend over and squint to get a good look through one of them. I found a pane that wasn’t sullied by smeary fingerprints and took pictures. The views of downtown, Busch Stadium and the river are pretty impressive, but you definitely want to try and do this on a sunny day with good visibility.

You also can stay up there as long as you like, but 10 minutes was plenty for me. And although the ride back down on the “Alien” pod takes a minute less than the ride up, it seemed much quicker. The bottom line? Whether you look at it as sculpture, the symbolic gateway to the West, America’s tallest monument or a tourist trap, the Arch is cool.

The Arch stands on the riverfront at the foot of Market Street. Note: Visitors must pass through a metal detector and have backpacks, bags and personal belongings checked.