Syon House, and its 200-acre (80 hectare) park, Syon Park, is in west London, historically within the parish of Isleworth, in the county of Middlesex. It belongs to the Duke of Northumberland and is now his family's London residence. The family's traditional central London residence was Northumberland House. The eclectic interior of the house was designed by the architect Robert Adam in the 1760s.