Tanzbrunnen

This guide to Tanzbrunnen in Cologne follows the peculiar power of the number eleven, from medieval numerology that made it the fools' number to the Elferrat council formed in 1823 that still wears pointed caps today. It also traces the site's engineering, from the walkable fountain rotunda architect Josef Op Gen Orth floated here in 1949 to the star-shaped fabric canopy Frei Otto stretched over the crowd eight years later. That same lightweight tent, built for a garden show, was designed by the man who later shaped the Munich Olympic stadium roof.