5 Questions About U.S. Landmarks We Bet You Can’t Answer

5 Why Does the Pentagon Take Up So Many Acres?

For years, the Pentagon was the world’s largest office building, boasting more than six million square feet of floor space. Last year, it was overtaken by a complex in India called Surat Diamond Bourse. This new building, devoted entirely to the luxury diamond industry, consists of nine different interconnected towers, so some might say it qualifies as a single building only on a technicality. 

The Pentagon is so large because it’s the headquarters of the Department of Defense, the single largest employer in the world. The DoD employs almost three million people, and 27,000 of them work in the Pentagon. The building is especially large because we built it during World War II, which was the most complicated challenge ever faced by the Department, or by anyone. 

None of that answers the exact question we asked. Even if the Pentagon has to contain six million square feet, why is it so spread out, across 30 acres? Buildings are almost never so flat. The Surat Diamond Bourse towers have 15 floors each, while the Pentagon has just five. Washington, D.C. doesn’t have the skyscrapers many other cities do (no building in that town should be higher than the Washington Monument), but plenty of its buildings have 10 floors or more. Why doesn’t the Pentagon?

Normally, a taller and narrower building would be the wiser choice. Land is scarce in most locations where a building this large is desirable. Plus, elevators move up and down, not side-to-side. But for a building to stand many floors tall, you need lots of steel, and during construction, they wanted to use as little steel as possible, to save the stuff for the war effort. By keeping the building low, they avoided using a steel frame and saved on the steel elevators they’d otherwise need. They also used asbestos tubes instead of steel ducts and concrete pipes instead of steel pipes. They saved some 38,000 tons of steel this way, more than enough to build an entire battleship. 

It made for a weird and wonky building. When the war was done, everyone assumed the Department of Defense would move elsewhere, and the temporary five-sided building they’d constructed would be converted to a warehouse or something. Somehow, that never happened. 

4 Where Is the Center of Gravity of the Space Needle?

The weight below an object’s center of gravity equals the weight above it. So, if you stumble on a giant silver monolith one day, you can assume the center of gravity is right in the middle:

Apply the “just point toward the middle” strategy to Seattle’s 500-foot Space Needle tower, and you’ll wind up eyeballing the center of gravity to be around 250 feet up. 

But wait. The Needle’s observation deck is a whole lot wider than any part below that. A whole lot of mass must be concentrated in this section of the building (insiders refer to this portion of a building as the “glans”). Maybe we should shift the arrow a bit upward to take that into account. 

That all sounds reasonable enough, but we’ve been played for fools. The actual center of gravity of the tower is more like just five feet from the ground. That’s well below the height of most people reading this. 

The building may look like a needle pointing from the ground to the sky, but a large bulk of the structure’s mass sits underground. The foundations run 30 feet below the surface, and these foundations weigh 5,840 tons. That handily outweighs the 3,700 tons that the visible portion of the tower weighs. In fact, that would seem to put the center of gravity even further down, moving it actually below the surface. Either way (and either weigh), it’s far below the initial 250-foot answer we offered. 

All towers have foundations that matter a whole lot, even if we don’t see them. Without proper foundations, towers would fall over, or sink into the ground, or maybe shoot straight to the Moon, depending on the exact physics in play. 

3 What Faces Did South Dakota Want to Carve into Mount Rushmore?

Mount Rushmore features the faces of four presidents — George Washington, Thomas Jefferson, Theodore Roosevelt and Abraham Lincoln. “Mount Rushmore” is the name of the mountain (one of its names, at least; the Lakota call it “Six Grandfathers”), while the memorial is named Shrine of Democracy. Clearly, the carving is a tribute to America’s history, which is why they stuck four heads of state up there.

It started out with a more narrow focus. First of all, the idea for the monument came from South Dakota specifically, rather than from the federal government that provided funding. This explains, of course, why they wound up carving this landmark in South Dakota, of all places. The South Dakota State Historical Society came up with the idea, as a plan to draw tourists to South Dakota. It would prove very effective at this. 

As it was conceived as a South Dakota attraction, it was originally supposed to be themed more to the region. Rather than depicting four presidents, it was supposed to depict figures from the Old West. These included Lewis and Clark and Sacagawea. The plans also included Lakota chief Red Cloud, Buffalo Bill and Crazy Horse, the last of whom is the subject of a different later mountain memorial that’s been under construction for decades.

A couple of those figures not only weren’t presidents — they fought in wars against the United States. Still, they’re part of the history of the land, and South Dakota wanted to honor them all. The sculptor they hired, Gutzon Borglum, had other ideas, and his ideas won out in the end. Borglum chose four presidents. Presidents or Old West figures, you’d think he could have picked six faces. The mountain was named “Six Grandfathers”; six would have been perfect.

If they had ended up carving Sacagawea and Red Cloud up there, some might say that’s more fitting for land that was considered sacred by the native people of the Great Plains. The native people of the Great Plains might disagree, saying they don’t want any carvings up there, they just want the land back. The Supreme Court ruled in 1980 that the U.S. had stolen this land from the Sioux, in violation of U.S. law, and the Sioux now have over $1 billion in compensation gathering interest waiting for them to collect.

2 Who Was the St. Louis Arch Accused of Plagiarizing?

Behold, the Gateway Arch of St. Louis, Missouri. The Arch measures exactly 630 feet tall and also exactly 630 feet wide. If you assumed the arch stood taller than its width, and you even still think that when looking at a photo of it, you have been tricked by an optical illusion.

St. Louis hosted a competition in 1947, so architects could submit designs for the monument the city planned to build. The winning idea of an arch led to some complications. The city constructed the two legs of the arch from the ground up, and people eagerly watched, assuming the legs wouldn’t meet and the city would have to start all over, but the calculations were accurate and the halves met up just fine. They met up a little too fine, actually. Thanks to the steel expanding in the heat, the two halves slammed together before the crew could insert a keystone in the joint. They had to douse the monument in cold water so it could contract a little, creating enough space to squeeze the keystone in. 

The arch design also attracted some criticism. The design looked suspiciously familiar to some people. Why, it looked incredibly similar to the Arch of Empire, a structure proposed by Benito Mussolini! Mussolini hadn’t personally designed the arch, as he had little education in engineering, but he approved its construction. The arch was supposed to welcome people to the Esposizione Universale di Roma, a World’s Fair scheduled for 1942. 

The Esposizione Universale di Roma was supposed to celebrate 20 years of Fascism, and Mussolini’s Arch was supposed to herald a revival of the Roman Empire. The Fair never took place, and the Arch was never constructed, because World War II interrupted everyone’s plans (and as mentioned above, also led to a shortage of steel). Still, architects remembered the plans, and they questioned why Gateway Arch designer Eero Saarinen was ripping off the recently deceased dictator of Italy. 

Other architects laughed off these criticisms and put an end to them. An arch is so basic a structure that it cannot be plagiarized, they declared. Though, if that were true, the Gateway Arch wouldn’t be much of a design, now would it?

1 How Long Does the Grand Canyon’s River Take to Reach the Ocean?

This question is particularly hard because most of us have no frame of reference. Just try searching the web for how long it takes water in general to travel down rivers to the ocean, and you’ll find this surprisingly difficult to find out. You will be taken to sites like Quora, where people have asked the question before, and Quora will helpfully list a bunch of “related questions,” which are not related at all, but no actual answer.

So, let’s start you off with some background info about another river so you can stand a better chance at answering our question about the Colorado River, which flows through the Grand Canyon. Water takes about three months to travel the length of the Mississippi River. That water’s speed averages out to about three miles per hour. The Grand Canyon is about 600 miles away from the Gulf of California. Also, there are 24 hours in a day, but we suspect you knew that already. Now, can you guess how long it takes water from the Colorado River to reach the ocean?

Here’s the answer: Water in the Colorado River never reaches the ocean. The river used to reach the ocean (the Gulf of California, like we mentioned), but since 1998, when we finished damming the river, all the water is instead diverted to agricultural projects. Very rarely, the river will swell so much that it surpasses the amount that we dam and the river flows to the ocean after all — this happened in 2018, for the first time since 1998. But in general, the water won’t reach the ocean. 

Not directly, anyway. We suppose it will eventually, once the water molecules become wheat, and the wheat becomes bread, and someone eats the bread, and the bread becomes glucose in their body, it turns back into water through respiration, they sweat that water out, and it evaporates, and the water vapor forms a cloud, and it rains into some body of water that does reach the ocean.

Naturally, the idea that the Colorado River no longer reaches the ocean is a bit sad for the people who remember when it used to, and anyone who could benefit from a bubbly river around there. On the other hand, it’s one hell of an accomplishment, diverting the flow in a way that we’re able to use every bit of that water. This world has only a tiny bit of fresh water compared to the huge oceans, and every river that meets the sea dumps its fresh water till it becomes salty and unusable by us. If there were a way to take the 600,000 cubic feet of water that the Mississippi discharges into the Gulf of Mexico every second, and magically teleport it to farms suffering from drought, we’d jump at the chance. 

Follow Ryan Menezes on Twitter for more stuff no one should see.