A Million Open Doors (1992) is a science fiction novel by American writer John Barnes, the first book of his Thousand Cultures series.

The story begins sometime in the 29th century on the planet Wilson (orbiting Arcturus) with a young man named Giraut and his romantic, swashbuckling friends, who are all members of the Nou Occitan culture and residents in the Quartier de Jovents, a sort of playground for teens and twenty-somethings who have not yet moved on to the more "grown-up" lifestyle of their parents.

Technologically safeguarded, these young adults have swordfights in the streets with "neuroducer" épées and frequent the taverns of the Quartier, living in an imaginative recreation of Occitan literature and the trobador tradition.

Thus, Aimeric and Giraut advise the rational council of the Caledonians to adjust their economy to that of the rest of the universe so that the springer will have as few adverse effects as possible.

When the Caledonians decide that Aimeric and Giraut, as well as the Interstellar government, are trying to usurp their power, they begin to try to seize back control of everything, and an urban conflict ensues.