Kew Gardens is a botanical garden in the Borough of Richmond upon Thames, Southwest London, founded in 1840 from the seventeenth-century exotic garden at Kew Park and the royal estates of Richmond and Kew. It consists of 300 acres of gardens and botanical glasshouses, over 30,000 different kinds of living plants, and over 7 million preserved plant specimens. The Temperate House, the largest Victorian glasshouse in existence, opened in 1863. The Marianne North Gallery, opened in 1882, houses North’s paintings of American, Asian, and South African plants. Kew Gardens has its own police force, Kew Constabulary, in operation since 1847.