[3] The mansion house at 194 Watford High Street was built for the Dyson family around 1775, although there are records of a brewery operating on the site since 1750.

The three-storey, red-brick house, built in the Georgian neoclassical style, is fronted by a three-bay pediment with a central bull's eye window, and flanked by two lower wings which were added circa 1807.

[10][11] Among the other works of art on display are oil paintings of the Dutch and Flemish schools, with works by Adam François van der Meulen, Klaes Molenaer, Pieter Neeffs the Elder and Adriaen van Ostade, as well as paintings by Turner, Peter Lely, Ronald Pope and Joshua Reynolds.

[12] A number of acquisitions for the fine art collection have been assisted by grants from the Art Fund, including paintings by Henry Edridge, Sir Hubert von Herkomer, William Henry Hunt and John Wootton, and a set of 21 engravings from the Illustrations of the Book of Job by William Blake.

[15] The museum holds an archive collection of documents, printed ephemera, photographs and diaries related to Watford townsfolk, local government, nobility and businesses.