The name "Cornhill" preserves a memory of the topography of the site upon which the Roman city of Londinium was built. The Romans constructed their fortress on the north side of the Thames because the natural topography boasted two hills rising to the two "extensive plateaux" later named Ludgate Hill and Cornhill (Sheppard 21) whereas the south side of the Thames consisted of the marshy mudflats typical of a tidal river. Ludgate Hill and Cornhill were bisected by the Walbrook River. -- Janelle Day Jenstad, 2002