The National Botanic Garden of Wales is in Carmarthenshire, south Wales. Opened in May 2000, it covers over 500 acres and includes the Great Glasshouse, the largest single-span glasshouse in the world. Inside are some of the most endangered plants on the planet from various geographical areas with a Mediterranean climate. Other areas worth visiting are the Japanese garden, the double walled garden, the tropical house and the series of garden lakes. There is also a research facility dedication to the conservation of biodiversity. So the collection includes both threatened Welsh plants as well as plants from around the world.