November 2nd marks 11 years since humans first floated on board the International Space Station. The anniversary also commemorates more than a decade of continuous human presence in space. Long before the success of this orbiting football field–size laboratory, the Soviet Union launched the world's first space station, Salyut 1, in 1971. Two years later, the U.S. sent its Skylab station into orbit, where its last crew stayed for 84 days. But it wasn't until 1986 that the Soviet's Mir pioneered long-duration spaceflight and international partnerships—125 astronauts and cosmonauts from 12 different nations made 17 expeditions to this station during its 15 years in orbit, with one cosmonaut, Valeri Polyakov, spending 437 days on board.

Space stations started out as any other technology does before it becomes a reality—as concepts. In the past century engineers, writers and even movie producers have created conceptual space stations that ranged from simple orb-shaped structures to elaborate multi-unit designs. The imaginations of innovators who dreamed deeply about humans living in space are featured in the following nine artists' representations.

View a slide show of the nine space station concepts.