Boston Common is one of America's oldest parks in the heart of Boston, offering recreation opportunities and a glimpse into history through numerous monuments from the past. Designated as a public space in the 1640s, British soldiers later camped here during the Revolutionary War. Part of the Freedom Trail, the park adjoins the Massachusetts State House and Beacon Hill. A favorite spot is the Frog Pond, which doubles as an ice skating rink. The park is the beginning of the Emerald Necklace, a seven-mile (12-kilometer) string of local parks designed by Frederick Law Olmsted, a popular landscape architect.