To build the world's largest jetliner in the 1960s, Boeing built the world's largest building. Construction began in 1966, and crews moved four times as much earth as was needed to complete the massive Grand Coulee Dam project on Washington's Columbia River. The original factory was completed in 1968. From its original size, it was expanded by more than 45 percent in 1980 to house the 767 assembly line, and another 50-percent enlargement was added in 1993 for 777 assembly. Each of the factory doors are roughly twice the size of an American football field.