The Eden Project is the largest greenhouse in the world and it's a project open to visitors, offering rides, tours, activities and courses. Opened in 2001, these domes provide examples of species around the world, each dome emulating a different biome. Each dome is built out of hexagonal plastic panels and views from far away might give the impression that it is a giant beehive. This greenhouse is a very cheap attraction if tickets are purchased in advance on the web. They cost between 36 and 39 pounds a day.