Once upon a time, a person's home was wherever they built it, and the places that didn't have homes were considered shared land. Then came the concept of purchasing private property and land grants and deeds, and poor people were out of luck. But in that transition period, people came up with schemes to work around that. One was the concept of tŷ unnos, a Welsh term meaning "house built in one night." It became a tradition that if one were to build an entire home in one night before the sun came up, they would own that house, plus however much land they could toss an axe to.
Young people would plan their adventures in building for a long time, making some components and gathering construction materials. Then on the planned night, all their friends and family would begin building when the sun set. These crude structures were merely four walls with a door and a roof, with a chimney because a fire was necessary. After the household was established, the tŷ unnos would be replaced by something more substantial. This tradition was not limited to Wales, though. A similar scheme existed under different names in Ireland, Italy, France, and in Turkey. Read about tŷ unnos and how that worked at Amusing Planet.
(Image credit: Steve Daniels)