Castries /ˈkæstriːz/, population 20,000, aggl. 53,639, is the capital and largest city of Saint Lucia, a country in the Caribbean. The quarter with the same name had a population of 70,000 on 22 May 2013 and stretches over an area of 80 km2 (31 sq mi). St Lucia's main post office is in Castries. Because most parts of the country do not use standard street addresses, mail is largely sent to P.O. boxes. Any mail sent without a town name ends up in the Castries post office. Castries is the birthplace of Arthur Lewis, winner of the 1979 Nobel Memorial Prize in Economics.