EVERETT, WA—Boeing’s factory complex here is the world’s largest building and has produced more wide-body planes than all other competing manufacturers combined. It also just got a lot bigger. The new additions are two buildings for Boeing 777X construction that increase the factory space by another 25 percent.

Boeing' massive production facility is more than 1 kilometer long and one-half-kilometer wide. It has six doors and each is the size of an American football field that depicting a company plane.

The industrial complex also three huge paint hangars, sprawling flight lines, a plane delivery center that is as big as an airport terminal, office blocks, and the new 777X wing assembly plant. The whole facility covers an area of 415 hectares.

Built in 1968, the plant doubled in size to accommodate production of the 767 in the late 1970s and was expanded again by 50 percent in 1993 to build the 777. Recently, the huge wing plant was constructed behind the main facility to build the composite wings for the 777X.

The factory has 26 overhead cranes that cruise on 72 kilometers of networked tracks and these cranes make 45,000 lifts a month to support the building of about 20 planes a month.