The earliest surviving detailed map of Moyse's Hall, Thomas Warren's map of 1741, shows that the Guildhall Feoffees also owned the property next to Moyse's Hall (to the left of the entrance front) and that this was a public house called the Castle Inn. Indeed, part of Moyse's Hall itself, the rooms to the left of the modern entrance, was used by the inn. Warren calls it 'The Mansion House belonging to the Castle.' In 1812, the Guildhall Feoffees sold the whole of the Castle Inn, including the Moyse's Hall rooms. However, when Moyse's Hall was converted into a museum in 1899, this part was bought by the Borough Council from Greene King Brewery and the Norman rooms were reunited as a single building. The Castle Inn has now been gutted, but a beer cellar still survives under Moyse's Hall as a reminder of its existence.

At the rear of the Norman core of Moyse's Hall is an L-shaped range of buildings now known as 41 Cornhill, part of which dates back to the early 16th century. There is some architectural and historical evidence to suggest that it was attached to Moyse's Hall from its earliest stages.

Thomas Warren's map of 1741 shows that 41 Cornhill was then owned by the Guildhall Feoffment Trust and formed part of the Bridewell. However, the Guildhall Feoffees sold it in 1812, when they also sold the Castle Inn. For much of the 20th century it was used as shops. In 1972 the Council bought it and opened two new museum Galleries in the part immediately behind, Moyse's Hall.