The gatehouse of the Bishop’s Palace is a Grade I listed building. Unfortunately, because of a number of insensitive alterations over the last 150 years, its current appearance is a bit of a mess. But at least it still exists, which is more than can be said for nearly every other medieval gatehouse in Exeter.
The core of the building dates to the 14th century and is perhaps contemporary with a major extension of the palace by Bishop Grandisson around 1340. Much of the gatehouse is constructed from rough blocks of purple volcanic trap, typically used for high status buildings in Exeter before the 1400s, although there has been a lot of patching during subsequent centuries. The arrow slits and the main entrance arch are original, even if they have been significantly restored. The arched window openings also perhaps date to the 14th century. There is evidence in the west end wall of a large, medieval pointed archway, now blocked. The Georgian sashes were added in the 18th century along with a new staircase. William Butterfield added the cusped Gothic stone windows in 1875 and seems to have raised the height of the building. The rooms built into the modern roof space are a particularly unfortunate addition.
It has all been so altered that it's hard to imagine what the building looked like when first completed. I don't know if any features of interest survive inside but it seems unlikely given the extent of the alterations. In the Westcountry Studies Library is an intriguing sketch made by John Gendell in 1829 right © Devon County Council. It is entitled 'Part of the Palace Gate being the only remains'. It shows a room strewn with barrels, above which can be seen a fine plasterwork ceiling of a late 16th century type. It is similar in style to an existing ceiling at St Nicholas's Priory. It seems likely that Gendell's sketch does indeed show the interior of the gatehouse of the Bishop's Palace. The ceiling was presumably destroyed either before or during Butterfield's 'improvements' as there is nothing to indicate it still exists today, either in the gatehouse or in any other building in Exeter.