Wow! Look what we did! We built this huge thing in the sky!” The words that came from US astronaut Sally Magnus the first time she docked at the International Space Station (ISS) expressed how totally awestruck she was. And for good reason.

When an astronaut finally pulls up outside the ISS after all the years of training, it’s hard to believe something so complex and massive is floating about 400 kilometres above Earth. Its lighting only adds to the dramatic effect: the illuminated parts are almost blinding in their vivid detail and crystalline clarity; the shaded parts almost invisibly black.

At some 360,000 kilograms, one of the largest and most complex engineering projects in history floats in a free-fall orbit, moving at the brisk 28,000 kilometres an hour it needs to keep aloft and going through approximately 16 sunrises and sunsets every 24 hours.

The giant H-shaped aluminium modular canister encloses a pressurised, temperature-controlled habitat. It needs to; in the hostile environment of space, temperatures can range from around –65.5 degrees Celsius to more than 150 degrees Celsius.

With an interior volume equal to that of two Boeing 767-300s, it has taken more than 80 space launches to assemble over the last ten years and has cost the United States US$44 billion to date. Partners Russia, Canada, the European Union and Japan have also invested heavily.

But the ISS was not the first space lab. In 1973, the 100-tonne Skylab was launched and built using leftover parts from the US Apollo project. Three US crews visited it and logged 3,000 hours of scientific experimentation and ten space walks, but it was plagued with meteorite damage and operational problems. By 1979, it was allowed to fall back to Earth, leading to NASA’s first ever fine for littering. But the idea of the ISS was born.

The international partners made a committment to make the project happen and in 1998, the first stage – the Russian Proton-launched cargo block Zarya, combined with the US Node 1 Pressurized Mating Adapter – became reality. During the last 11 years the ISS has been assembled piece by piece – and it shows.

With 2,500 square metres of electrical power-generating solar panels, a 110-metre-long body of different-shaped sections stacked together like a science project, shiny foil patches and engineering arms hanging out, it looks like it would never fly in a million years. But it does, and with ground support from more than 100,000 people at 500 global facilities, the ISS is open for business 24/7.

In fact, for the crews it’s just another workplace where there’s a job to be done – but with an incredible view from the window.