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.Castries is on a flood plain and is built on reclaimed land. It houses the seat of government and the head offices of many foreign and local businesses. The city is laid out in a grid pattern.