St John's Green is marked on Chapman & Andre's 1777 map of Colchester, located adjacent to (in front of) St John's Abbey Gate. The map is annotated and records, 'Here the Midsummer Fair is Kept'.<1>

Buildings front the green on the north and west sides, the walls of St John's Abbey on the east and south sides (with St Giles' Church on the NE. side), and a gravel pit on the SW. side.

The green is shown as an open area on Speed's map of 1610.

The green is still extant, although reduced in size.

A chapel dedicated to St Thomas (MCC424) was recorded from the early 13th century and may have been located on St John's Green, where a chapel with the same name was known to exist in the 15th century. A second chapel on St John's Green was dedicated to St Mary (MCC422), but was not recorded until the second half of the 14th century.<2><3> No archaeological of either has been discovered and the exact site of each chapel remains to be established; presumably both were demolished following the Dissolution.