 Charles Knight devoted an entire section to markets in his pictorial essay, "Pictorial Half-hours of London Topography," (1851) in which he identifies the main wholesale markets as the Corn Market; the Coal Exchange; Billingsgate - the main fish market; Smithfield - a cattle market since at least 1150.Retail meat markets include Newgate; Whitechapel; Newgate; Newport, Oxford; St George's and Shepherd's Market in Mayfair.Produce markets included Covent Garden, which Knight considered to be the 'pre-eminent' vegetable market; Farringdon Market between Holborn Hill and Fleet Street; Spitalfields - the largest potato market in London; Portman Market, Hungerford Market and Leadenhall Market- a mixed produce and meat market.