Forty Hall is located in the north of the London Borough of Enfield, the northern-most borough of London. The hall and formal park are located on the top of Forty Hill, a level gravel plateau standing above the flood plain of the Lea to the east, and the valley of the Turkey Brook to the north and west. The park slopes down into the valley, where the remains of old ponds lie on the London Clay. A loop in the former course of the New River forms the boundary of much of the estate, though this has since been re-routed to the east. To the north are Whitewebbs and Myddelton House. The road to the east was formerly the main route from Enfield to Waltham Cross, but traffic has been re-routed towards to A10.
The house was built between 1629 and 1632. It is generally said to have been built by Sir Nicholas Raynton or Rainton, a wealthy London haberdasher and Lord Mayor of London from 1632 to 1633. However Tuff states that it was built by Sir Hugh Fortee and bought by Raynton, quoting a 1635 survey describing a copyhold house some time Hugh Fortee's, and late Sir Thomas Gurney's. Lambert also gives Fortee as the origin of the name.
The detailed history of the house has until recently been poorly understood, since it is known to have been built in the 1620s, but has the external appearance of an 18th century house. A detailed examination was carried out for Enfield council as part of the Forty Hall Conservation Plan. This concluded that the house was probably not designed by a famous architect such as Inigo Jones, but by a 'clever artisan builder'.
The original square house was not altered much in the 17th century other than a small extension to the north-west in 1636. On 1640 Rainton was imprisoned for refusing to help Charles I raise a loan. He died in 1646 aged 77 and was buried at St Andrew's Church in Enfield. The hall then passed to his son, also Nicholas. He was able to extend the estate northwards by buying and demolishing neighbouring Elsyng Palace in 1656. In 1696 the hall passed to John Wolstenholme (probably a descendent of the financier and merchant of the same name and member of the Virginia Company), who carried out major refurbishment possibly following a fire, including construction of an extension to the south-west, and planted the avenue. In 1740 the house passed to Eliab Breton, who remodelled the ground floor. Later owners included Edmund Armstrong (1787) and James Meyer (1799), whose family built the nearby Jesus church in 1835. In 1894 the hall was bought by Henry Carrington Bowles of neighbouring Myddelton House for his son Major Henry Ferryman Bowles (1858-1943), MP for Enfield and later 1st Baronet Bowles. In 1897 there were further changes including enlargement of the south-west wing. In 1951 the Bowles family sold it to the Municipal Borough of Enfield, the predecessor of the London Borough of Enfield. It has since been used as a museum.
The museum focuses on the history of the area now covered by the London Borough of Enfield, with an emphasis on household objects, including complete tea and dinner services. Seventeenth and eighteenth-century pottery includes English tin-glazed ware and stoneware, creamware, pearlware, black basalt ware, German stoneware, and Chinese and English porcelain. 19th and 20th-century china includes china by Royal Doulton, Moorcroft, Wedgwood, Minton and Poole Pottery, and decorative work by Clarice Cliff, Susie Cooper, Charlotte Rhead and Keith Murray. Glassware includes wine glasses, flasks, decanters, phials and bottles.
In addition the museum holds finds from excavations by the Enfield Archaeological Society. Roman pottery and glass includes a complete brown glass flagon. Later (15th to 17th century) finds from Elsyng Palace include pottery, glass and polychrome, tin-glazed ware tiles.
The estate of around makes up part of the London green belt. Around the house are formal gardens and a small lake. The remainder includes a park that is open to the public and a farm. An avenue of trees runs down the hill from the house into the valley of the Turkey Brook, also known locally as Maidens Brook. The northern and much of the southern boundary are marked by the former course of the New River.