Winfield House is an English townhouse in Regent's Park, central London and the official residence of the United States Ambassador to the United Kingdom. The grounds are 12 acres (4.9 ha), the largest private garden in London save for that of Buckingham Palace.

Regent's Park is one of the Royal Parks of London. It occupies 410 acres (170 ha) of high ground in north-west Inner London, administratively split between the City of Westminster and the Borough of Camden. In addition to its large central parkland and ornamental lake, it contains various structures and organizations both public and private, generally on its periphery, including Regent's University and London Zoo.