Located at Everett, 50km north of Seattle in the Unites States' north-west, the almost 100 acre (40.47 hectares) factory houses Boeing's 747, 767, 777 and new 787 aircraft production lines. About 25,000 people work at the site, which boasts its own security force and fire department, a fully equipped medical clinic, a childcare centre, a water treatment plant, its own electrical sub-stations, and 19 cafeterias which serve around 17,000 meals per day.

They say 2142 average-sized American homes could fit inside the factory. Just the hangar doors are each roughly the size of an American football field. You can visit the factory all year round. From balconies overlooking the factory floor, you can watch as workers get around on bicycles beneath ceiling-mounted cranes which move aeroplane sections around the building. Seeing how it all goes together is awe-inspiring. Peering into the chaos of an unfinished fuselage or cockpit, you can begin to grasp just how mind-bendingly complex these machines are.

Most of the aeroplane components (a 747 is made up of about six million) are manufactured elsewhere and come to Everett by truck, ship, rail and jet. Assembly then takes around four months. Each plane is assembled in sections, which are wired up and fitted out before being joined together. The planes are then towed to a final assembly area where seats, carpet and other interior fittings are added.

Planes are then taken to a separate hangar to be painted. Up to 272kg of paint is used on bigger jets. The planes are then tested on an adjoining air field and taken for two test flights before finally being delivered to customers. You can also visit the new nearby Future of Flight Aviation Centre, featuring interactive exhibits designed to appeal to the whole family.

You can digitally design and test your own jet, take a ride on a flight simulator, and watch an extraordinary time-lapse film of the complete assembly of a 777. You can also pop into the Boeing store to take away a souvenir, anything from T-shirts to model aeroplanes.

While the Boeing factory is Seattle's top tourist attraction, the city, and Washington state, have much else to offer. If after all that you haven't had enough of aeroplanes, you can also visit the Museum of Flight, closer to the city. For something different, visit the art museum, aquarium or zoo; for incredible views on a clear day, get to the top of the Space Needle tower, in the city centre; or get out into the spectacular countryside - Mt Rainier and the Cascade Mountains are considered particular highlights.

IF YOU GO: Air Canada (1300-655-767, http://www.aircanada.com) now flies directly from Sydney to Vancouver, in Canada, every day. From Vancouver it is just a half hour flight to Seattle.

For information about Boeing tour times and bookings, visit http://www.futureofflight.org. The website also contains handy information about nearby accommodation and other attractions. Children must be at least 122cm tall to go on the tour. Wheelchair access can be arranged with seven days notice. Unfortunately, photography is not allowed inside the factory.

For more general information about Seattle visit http://www.cityofseattle.net. The writer was a guest in Seattle of Boeing and Air Canada.

AAP