one of the notable botanical gardens of Europe. Founded in 1759 on part of the ancient fortifications of Copenhagen, the garden occupies more than 9 hectares (24 acres) and has about 15,000 kinds of plants, both under glass and outdoors. The outdoor plantings are surprisingly rich, considering the northern climate (latitude 55° N); except for summer annuals, all plants, including many handsome specimen trees, are perennials. A large greenhouse-conservatory covering 3,000 square m (32,000 square feet) displays exceptionally large collections of orchids from Thailand, begonias, and ferns. The garden also has a special air-conditioned greenhouse that can re-create environments suitable for Arctic plants. The university's botanical museum and herbarium are housed in a building situated within the garden, giving the garden staff ready access to reference works and more than 2 million dried plant specimens.