In 1982, artist Agnes Denes proposed a monumental artistic planting in the wilderness of Finland. Tree Mountain was created by 11,000 people from all over the world each planting a single tree in a specifically designed pattern that evokes ancient artworks as well as mathematical precision found in many of the works of painting masters. Planting took place over four years, from 1992 to 1996, and resulted in the world's first virgin forest built by humans. Check out this amazing artwork, meant to last for hundreds of years.