Hatfield, town (parish), Welwyn Hatfield district, administrative and historic county of Hertfordshire, southeast-central England. It is located on the old Great North Road north of London.
Hatfield House, the home of the Cecil family, stands on the site of Bishop John Morton of Ely’s palace (completed 1497). A row of small Georgian dwellings remains in Fore Street in the old town. The Eight Bells Inn was reputedly the scene of one of highwayman Dick Turpin’s escapades. The Church of St. Ethelreda contains the Salisbury Chapel (1618).
Hatfield, one of eight new towns near London, was designated in 1948 by British planners to accommodate the overspill population. It lies between the Barnet bypass, Hatfield Park, and Welwyn Garden City. The site was already well endowed with industry, principally aircraft manufacture and general engineering, prior to its establishment; later an electronics sector was added. The city is home to the University of Hertfordshire (1992), formerly Hatfield Polytechnic (1952). Pop. (2001) 29,616; (2011) 39,202.