International Space Station (15 nations, 1998–present)

Assembly of the International Space Station began in November 1998 with the launch of the Russian Zarya module, and the station has been continuously inhabited since November 2, 2000 — over 25 years of unbroken human presence in space. A collaboration between NASA, Roscosmos, ESA, JAXA, and the Canadian Space Agency, the ISS cost approximately $150 billion to build and operates at an altitude of 408 km, completing 16 orbits per day. More than 3,300 scientific experiments have been conducted aboard, spanning cancer research, fluid physics, materials science, and human physiology in microgravity. The ISS demonstrated that nations that cannot agree on anything else on Earth can work together flawlessly in orbit.