Marietta, Georgia (CNN) One of the largest airplanes in the world -- a jet that forever changed America's military and airline industry -- is turning half a century old.

When you see a C-5 Galaxy on the ground for the first time, the first thing that strikes you is... it's freakishly huge.

Length: 247 feet. Wingspan: wider than a Boeing 747-400. The pilot sits about three-and-a-half stories high in the cockpit, and the plane's T-tail stands as tall as a six-story building.

The US Air Force C-5 transport jet hits the big 5-0. Did we say big? Yes. Freakishly big.

The transport jet certainly must have turned heads on June 30, 1968, when it first took off from a runway at Lockheed Martin's historic factory north of Atlanta. Until the 1980s, it reigned as the world's largest airplane.

For the first time, the C-5 made it possible for 70-ton tanks, fighter jets, multiple helicopters or other huge cargo to go just about anywhere in a matter of hours instead of weeks aboard a ship.

It made the Pentagon more nimble. More flexible to quickly shifting events. And it redefined how military forces — and lifesaving humanitarian aid — could be deployed.

The C-5 is credited with spurring the development of new engine technology that benefits virtually all air travelers today.

More about that in a second. First, let's talk about this plane's superpowers:

Its landing gear can kneel toward the ground to make it easier to load

The C-5's nose lifts up, revealing a huge cargo hold that can be loaded and unloaded from the front and the back

Its cargo hold is 19 feet wide and 143 feet long -- longer than the Wright brothers' first flight back in 1903.

The plane has an upper deck with airline-style seats that can carry around 73 troops, or other passengers

WOWZA! The US military's largest aircraft, the USAF Lockheed C-5, has arrived at #OSH16! #avgeek pic.twitter.com/olghYrLvhD — Thom Patterson (@thompatterson) July 26, 2016

Birthday party

Hitting the big 5-0 usually calls for a celebration. So last Tuesday, at the same Georgia site where it flew for the first time, politicians, Air Force generals, business executives and assembly-line workers gathered under a big tent to mark the jet's golden anniversary.

A newly upgraded C-5M, the big bad belle of the ball, sat nearby, filling up the background, standing on its 28 wheels, holding its T-tail proudly in the air and acting all nonchalant about those four beautifully gargantuan engines hanging off its wings.

"This airplane has served as an ambassador of the skies -- both for both war and for peace," Georgia Gov. Nathan Deal told the crowd.

US Air Force brass and Lockheed Martin officials celebrated the C-5 Galaxy's 50th anniversary Tuesday in Marietta, Georgia.

Recent peaceful missions include delivering humanitarian aid in the US -- like C-5s did last year when they hauled medical teams and emergency supplies to help victims of Hurricanes Harvey, Irma and Maria.

After ISIS forces destroyed a key bridge across the Tigris River in Iraq, the Air Force said 11 C-5s flew 5,000 miles each way to deliver materials to build a floating bridge in 2017, helping hundreds of thousands of evacuees who needed to cross.

Fans of the C-5 love to brag about these missions:

This plane's legacy has touched billions of travelers

If you travel by air, it's likely your life has been touched by the C-5's legacy. The plane is largely responsible for the development of modern airliner engines that fly billions of passengers each year.

When the C-5 was on the drawing board, engineers created new engines called high-bypass turbofan engines that were powerful enough to get this monster airborne. High-bypass turbofan engines are wider than the turbojet engines that were common on 1960s airliners.

The magic is in the fans — which suck in a lot more air in the front, while the engine pushes a much stronger force out the back.

"Most of the thrust from the C-5 engine comes from that giant fan in the front. It's very fuel-efficient," said Lockheed Martin aviation historian Jeff Rhodes. "The 747, DC-10, L-1011 — all the wide-body airliners — came almost on the heels of this."

High-bypass turbofan engines on today's airliners allow us to fly farther requiring fewer engines and less fuel than the old-style turbojets.

Overcoming some early troubles

The C-5 had a rather difficult time at first. A tragic crash during the evacuation of orphan refugees from South Vietnam in 1975 killed 202 people.

In the '70s, cracks were discovered in some wings of the C-5As — the first version of the plane. C-5A wings were eventually replaced.

The 1980s, '90s and 2000s saw the C-5 taking part in high-profile aid missions worldwide , including deliveries to cleanup a catastrophic oil spill in Alaska's Prince William Sound, supplying refugees from wars in Rwanda and Kosovo, feeding the hungry in Somalia and helping flood victims in Mozambique. During the 1980s, the C-5 lost its status as the world's largest military production aircraft when a a new transport jet called the Antonov AN-124 Ruslan joined the fleet of the Soviet air force.

"The C-5 has been emblematic of the US resolve to do good in the world by providing an unmatched capability to help people anywhere, when they need assistance," said Dr. Doug Lantry, curator and historian at the National Museum of the US Air Force.

In addition to being a marvel, the plane has been somewhat of a disappointment, too. "It's performed very well in its missions, both humanitarian and military, but it has had frustrating reliability problems," Lantry said. "The C-5 modernization program should help the plane fly through around 2040 and achieve it's original promise with greatly improved reliability."

These modernized airlifters are called C-5M Super Galaxies.

"Over 60 different improvements were made to the C-5M over the previous version," said Air Force Brig. Gen. Kenneth Bibb, commander of the Air Force tanker airlift control center at Scott Air Force Base in Illinois. "Now it can go much farther, climb much higher and is much more fuel efficient. You can go from the East Coast to Turkey — or from the West Coast to Japan -- without refueling."

If you're feeling the need to see one of these mega machines in real life, C-5s from Travis Air Force Base will be visiting the following events this summer:

It's a chance to take a stroll through the cavernous cargo hold of an amazing jet that really has changed the world.