Nantucket is located 30 miles (48.3 km) south of Cape Cod. It is also nicknamed "The Grey Lady" due to occasional intense fog. Nantucket was formerly the world''s leading whaling port. Herman Melville comments on Nantucket''s whaling dominance in Moby Dick. Nantucket is a tourist destination and summer colony. According to Forbes Magazine, in 2006, Nantucket had the highest median property value of any Massachusetts zip code. The island features one of the highest concentrations of pre-Civil War structures in the United States.