For some time during the eighteenth and nineteenth century, the market place in Peterborough was known as Market Hill.
The earliest reference from the papers is an advert from 1736 for the letting of 'An old-accustom'd Grocer's Shop... situate upon the Market Hill in Peterborough'.
A reference to the Talbot Inn from 1774 states it is 'on the market hill'. This continued until an 1898 reference to J. A. Bingham, Auctioneer of Market Hill, Peterborough. Currently the area is known as Cathedral Square.
Cambridge and Chatteris still use the word for their market places. It certainly is an odd choice of word for towns in areas with little or no hills!
Source: Stamford Mercury, Thursday 5th August 1736, page 4, col 1