Vincent Square is a grass-covered square in Westminster, London, England. It is London's largest privately-owned square,[1] covering 13 acres, lined with mature trees including London Planes. In among a network of backstreets, it chiefly provides playing fields for Westminster School, who own it absolutely; otherwise, it functions as a green lung and a view for the homes, hotel and other organisations adjoining.[2] Nine of its adjoining buildings have been given strict statutory architectural recognition and protection. The Liberal Democrat Headquarters, housing one of Parliament's three largest political parties, is based at 1 Vincent Square.[3]