Green Park is one of the royal parks of London, located in Westminster in the city's center. The 40-acre park was first enclosed in the 16th century, and it was originally swampy burial ground for lepers from the nearby St. James' Hospital. In 1668, King Charles II of England became owner of the park, and he laid out the park's main walks, brick walls, and an icehouse to supply him with ice for cooling drinks in the summer. It was an isolated area well into the 18th century, being haunted by highwaymen, who even managed to rob Prime Minister Horace Walpole. During the 18th and 19th centuries, it was popular for ballooning attempts and firework displays, as well as for duelling. In 1820, it was landscaped, and it became notable for having no lakes or buildings and minimal flower planting.