Castries is the capital and largest city of Saint Lucia, an island country in the Caribbean. The urban area has a population of approximately 20,000, while the eponymous district has a population of 70,000, as at May 2013. The city covers 80 km2 (31 sq mi).

Saint Lucia is an island country of the West Indies in the eastern Caribbean. The island was previously called Iouanalao and later Hewanorra, names given by the native Arawaks and Caribs (respectively), two Amerindian peoples. Part of the Windward Islands of the Lesser Antilles, it is located north/northeast of the island of Saint Vincent, northwest of Barbados and south of Martinique. It covers a land area of 617 km2 with an estimated population of over 180,000 people as of 2018. The nation's capital and largest city is Castries.