St James's Hill postmill stood on this site -1235 to 1611+ and it is the oldest site in the city of Norwich. There was a mill 'outside the City ditch' in 1235 and a windmill to the Northeast of the city was disused by circa 1275. A mill stood on this site in 1355 and one was marked on maps of 1558, 1581, and 1650. The 1696 map shows St. James's Hill but no mill. This could indicate that the mill had stood to within a few years of that date. The mill was almost certainly a sunk post mill with four common sails and one pair of millstones. It stood about 100 feet' above sea level. It is not known how many mills occupied this site.

The site is easily identifiable today, the actual site of the mill being marked by a bench and lies to the west of Britannia Rd.