I visited the National Air and Space Museum's lesser-known second location. One exhibit stopped me in my tracks.

Unlike at the National Air and Space Museum's flagship DC location, where timed-entry tickets help manage large crowds in the smaller space, reservations are not required at the Udvar-Hazy Center.

Admission to the museum is free, and parking costs $15.

At 164 feet tall, the observation tower educates visitors about the history of Air Traffic Control and provides a 360-degree view of the modern airport in action.

Inside the tower, I watched planes take off and land at Dulles Airport while listening to live Air Traffic Control audio.

Visitors can watch restoration work happen in real time from a balcony with floor-to-ceiling windows overlooking the hangar.

Among the works-in-progress are "Flak-Bait," a Martin B-26 Marauder that flew 202 combat missions during World War II and participated in D-Day, and a Sikorsky JRS-1 seaplane that was present at Pearl Harbor when it was attacked on December 7, 1941.

On August 6, 1945, the Boeing B-29 Superfortress bomber Enola Gay dropped the first-ever atomic bomb used in warfare on Hiroshima, killing at least 70,000 people.

The "Little Boy" atomic bomb weighed 9,700 pounds, forcing the aircraft to remove most of its protective and defensive armament in order to carry the enormous weight.

The Enola Gay exhibit sparked controversy when the plane was first displayed in 1995, as veterans' groups and anti-war activists debated how the historical narrative around the use of the atomic bomb should be presented.

In the 1950s, Boeing set out to build a jet aircraft that could function as a passenger aircraft, a cargo plane, or a tanker used for mid-air refueling.

Boeing began building this prototype jet in 1952, and it flew for the first time two years later. It traveled 100 miles per hour faster than the de Havilland Comet, the world's first jetliner developed in the UK, and had a range of over 3,500 miles, revolutionizing the air travel industry.

Known as "Dash 80," the developed version of the aircraft entered service as the first jetliner in the US, the Boeing 707.

The governments of Britain and France collaborated to create the first supersonic commercial jets, which operated commercially from 1976 to 2003.

Traveling at twice the speed of sound allowed the planes to cross the ocean in record time. Concorde's fastest flight from New York City to London lasted just 2 hours, 52 minutes, and 59 seconds.

The museum's Concorde jet, which flew for Air France, measures 202 feet and 3 inches long with a wingspan of 83 feet and 10 inches.

The Lockheed SR-71A, a supersonic reconnaissance aircraft, was designed to fly high and fast enough to avoid Russian missiles during the Cold War. It was capable of flying at an altitude of over 85,000 feet at speeds of over three times the speed of sound, or approximately 0.7 miles per second.

The aircraft became known as "Blackbird" for its black paint that was capable of absorbing radar signals.

This Blackbird logged 2,801.1 hours of flight time over 24 years of service before retiring in 1990.

It's hard to capture the full scale of Discovery in a photo, but I found it awe-inspiring to see such an enormous, historically significant spacecraft in person.

The shuttle measures 122 feet long, 78 feet wide, and 57 feet tall, towering over the other artifacts in the hangar. When fully loaded for missions, the orbiter weighed around 250,000 pounds.

Discovery flew its first mission in 1984 and returned from its last in 2012, spending a total of 365 days in space.

Among its many historic accomplishments, Discovery deployed the Hubble Space Telescope in 1990 and became the first space shuttle to dock with the International Space Station in 1999.

The backpack propulsion device, powered by nitrogen jets, allowed McCandless to fly around 300 feet away from the space shuttle Challenger. His untethered spacewalk was immortalized in an iconic photo of the lone astronaut floating above the Earth.

My phone's step counter recorded nearly 10,000 steps on the day I visited the museum. There's an incredible amount of ground to cover and objects to see.

I can't believe I didn't know that the National Air and Space Museum even had a second location when I started planning my visit to Washington, DC. Now, I'm recommending it to all of the air and space enthusiasts I know.