2020 has been a tough year for aviation, and one of the most significant casualties when it comes to the industry is the Boeing 747. The Queen of the Skies is being retired at a rapid rate. Therefore, let's look at some of the most interesting units of the jumbo over the decades.

Across five decades, over 1,500 Boeing 747s have been produced. Undoubtedly, there are countless compelling units that have hit the skies. Nonetheless, this list will cover some of the ones that have had a particularly unique story.

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Flying penthouse

When the 747 was introduced in 1970, carriers were excited to be part of the widebody revolution. To stand out from its competitors while offering a unique first class experience, Delta Air Lines launched the "world's first flying penthouse apartment" on its jets.

Customers with tickets for the penthouse would see luxury features such as a coffee table with four wide deluxe seats that could swivel and recline. There was a two-seat sofa on top of a soft carpet. The ambient lighting and stereo sound also set the mood. A private lavatory, bar, and galley could be found onboard. The airline's first 747-100 arrived with registration number N9896. It was delivered on October 2nd, 1970.

Flying high

NASA took on a former Pan Am and United Boeing 747SP. Registration N536PA arrived at the space agency's facilities in October 1996, and it underwent a transformation into the Stratospheric Observatory for Infrared Astronomy (SOFIA). It held a 17-ton, 8-foot-wide infrared telescope mounted behind a huge sliding door.

NASA highlights that the plane flies into the stratosphere at 38,000-45,000 feet. This move puts it above 99% of Earth's infrared-blocking atmosphere. Therefore, astronomers can study the solar system with methods that are not possible with telescopes on the ground.

Diving low

There is a 70m-long decommissioned Boeing 747 submerged below water near Bahrain International Airport. It is part of the world's largest underwater theme park that will cover an area of 100,000 square meters. Bahrain's authorities promote the plane as the largest aircraft ever to be submerged, and divers from across the globe have been keen to tour the interior of the jet while underwater.

Record-breaking missions

On May 24th, 1991, an El Al Boeing 747-200 cargo aircraft airlifted at least 1,086 Ethiopian Jews from Addis Ababa to Israel as part of Operation Solomon. Moreover, two babies were born on the way. This feat broke the Guinness World Record for the greatest number of passengers on a single plane at one time.

This plane played a major role in Operation Exodus. The mission brought hundreds of thousands of Jews around the world to Israel following the end of the Cold War.

Veteran soldier

The United States owns four 747-200 spinoffs called the Boeing E-4B. These planes form part of the National Military Command System for the President, the Secretary of Defense, and the Joint Chiefs of Staff.

The oldest of these units is the one with serial number 73-1676. This veteran is 47 years old and continues to serve the country. This factor makes the plane one of the oldest 747s still in operation.

It can be deployed as an aerial command center in case of a national emergency where ground command and control centers are out of action. Moreover, it can provide the US' leadership with secure communications and control centers for giving orders during wartime and coordinating activities with military services.

Plenty to choose from

Altogether, the Boeing 747 has served generations of passengers for half a century. Many moments would have been made on these jets across the globe. However, this list covers some of the unique models over the decades.

What are your thoughts about the most interesting Boeing 747s? Are there any units that you find particularly compelling that are not on this list? Let us know what you think in the comment section.