English: This engraving made by N. Calcott in 1770 and engraved by Orlando Jewitt shows the North Gate of the city of Oxford, looking southwards down Cornmarket, just before it was demolished. The tower of St Michael-at-the-Northgate Church on the left, and part of the Bocardo Prison is on top of the gate.

Until 1771, the North Gate spanned Cornmarket immediately to the north of St Michael’s Street and St Michael-at-the-Northgate Church. Hence Cornmarket was known as North Gate Street until 1536, when a covered area was erected there to facilitate the selling of corn. Extracted from "Oxford History: City Wall"

http://www.oxfordhistory.org.uk/city_wall/02_north_gate.html