The largest building on Earth is not a palace, stadium, or airport terminal. It is a working factory, and its scale is so extreme that it once generated clouds indoors.
The Boeing Everett Factory, located in Washington State, holds the title of the world’s biggest building by volume. The structure encloses more than 472 million cubic feet of space and covers roughly 98 acres under one roof. To put that into perspective, the original Disneyland park in California spans about 85 acres, meaning the entire theme park could fit comfortably inside the factory.
The facility opened in 1967 and was built for a single purpose: producing Boeing’s revolutionary 747 jumbo jet. At the time, the aircraft was two and a half times larger than existing commercial airliners, and no factory on Earth could accommodate it. Boeing’s leadership approved an unprecedented gamble, investing over $1 billion in construction, more than the company itself was worth at the time.
Courtesy: Boeing
The site chosen was a former military airfield just 22 miles north of Seattle. The location allowed Boeing to stay close to its engineering base while giving it the space needed to build something entirely new. Construction was completed in just over a year, an extraordinary feat given the scale involved. Crews moved around four million cubic yards of earth and even built a dedicated railway to haul material away.
When the factory first became operational, its sheer size created an unexpected problem. Moisture from human activity and aircraft assembly would rise toward the 90-foot ceiling and condense, forming clouds inside the building. The issue was later solved with large-scale air conditioning, but the episode cemented the factory’s reputation as a structure on a different scale entirely.
Over the decades, the Everett site has expanded repeatedly. New sections were added for the 767 in the late 1970s and again in the 1990s for the 777. Today, the complex also supports production of the advanced 777X, including robotic fuselage assembly and composite wing fabrication.
Courtesy: Boeing
Around 36,000 people work on the site each day across multiple shifts. Many are not directly involved in aircraft assembly. The factory has its own fire department, medical clinic, child-care facilities, water treatment plant, and banking services. An underground tunnel system stretches more than two miles, with bicycles and vehicles used to move workers without disrupting production.
Despite its industrial purpose, the building has become a major tourist attraction. Hundreds of thousands of visitors take guided tours each year, drawn by the scale alone. Standing on the factory floor, with wide-body airliners dwarfed by the structure around them, it becomes clear why the Everett factory remains unmatched.