In July 1518, a woman named Frau Troffea stepped into a street in Strasbourg and began to dance. She didn't stop. She danced for days. Within a week, 34 others had joined her. Within a month, around 400 people were dancing uncontrollably in the streets, unable to stop even as they collapsed from exhaustion and bleeding feet. The baffled city authorities decided the only cure was more dancing, so they built a wooden stage and hired professional musicians to play for the afflicted. It didn't help. Some of the dancers reportedly died. To this day, no one has a definitive explanation for what happened.