End of an era: United bids farewell to the Boeing 747—Here's a look at the 'Queen of the Skies'

A chapter of aviation history closes Tuesday when bids farewell to the 747, the jumbo jet that made air travel way more affordable for millions of people around the globe.

The double-decker plane with the humped fuselage is one of the world's most recognized planes. But after flying the four-engine, fuel-guzzling plane for decades, United and other airlines are retiring the so-called Queen of the Skies in favor of sleeker, more cost-efficient models. The planes are used frequently for cargo, which was the reason for the plane's design. Some models were given a hinged nose to allow for easy loading of goods.

United's first 747 took off from San Francisco and flew to Honolulu in 1970. It's repeating that route for the final passenger flight Tuesday, complete with a crew dressed in 1970s uniforms. Smoking will not be permitted, however.

In a sign of how efficient modern planes have become, last month , and new, single-aisle Boeing 737s will likely do the job.

will retire its Boeing 747 fleet by January, the last U.S. airline to do so. But the plane will live on as a workhorse cargo jet, flown by and others.

Here's a look at the Boeing 747, and how it changed the world from its introduction nearly five decades ago:

Joe Sutter, who died last year, led the engineering team that designed the Boeing 747 in the mid-1960s. It took 50,000 employees to bring the plane to life. Boeing says it took 29 months from "conception to rollout," which earned the team the nickname "The Incredibles." Below is a prototype of the jumbo jet in 1968.

The 747's first flight was in February 1969. It entered into commercial service in 1970. The plane was more than 231 feet long and its tail was taller than a six-story building.

Now defunct Pan Am operated the first commercial 747 flight, in January 1970 from New York to London.

Orders rolled in quickly from airlines, including PanAm and TWA. The airlines were eager for the glamour buy and to fill the large planes with thousands of members of the new jet set. Below, airplane tails in 1970.

This mockup shows a configuration of a Boeing 747 that would make any coach-class veteran drool.

Air travel, even in the 1970s, was a luxury, and service aboard the 747 in the early days was elaborate compared with the no-frills era of modern air travel.

Decades before Gulf carriers introduced their flashy cabins, posh lounges were the place to see and be seen in the 1970s. Frank Sinatra Jr. once performed in an American Airlines 747 lounge (with a piano) on a red-eye flight from Los Angeles to New York, an attempt to draw more passengers. The planes could fit some 500 people, and later, airlines got rid of the spacious upper-deck lounges and focused on fitting as many passengers as possible into the plane, which made travel more affordable but less comfortable.

NASA used modified Boeing 747s from 1974 for activities including the study of air turbulence from large aircraft to the more glamorous job of ferrying space shuttles like the Columbia.

The hinged nose of the 747 cargo version allows for easy access to its cavernous interiors.

Cargo is keeping the Boeing 747 alive, even if airlines are turning their backs on the aircraft. UPS last year ordered 14 747-8 freighters, and a and air freight could keep them full in the future.

Two Boeing 747-200Bs make up the Air Force One fleet. President late last year complained about the cost of the scheduled replacement of the jets,

Correction: An earlier version of this story misstated the timing of Trump's Air Force One tweet.

Delta is also retiring its Boeing 747 fleet this year, replacing the jumbo jets with the twin-engine .

British Airways recently announced that it will retire its 747 fleet by 2024.

As the plane becomes a rarer sight at airports, passengers still often stop to get a look at the "Queen of the Skies."