sentences:  The archaeologists Oliver Creighton and Robert Higham go so far as to consider the building to be unique within Britain, as God's House was an extension of an existing building, and the West Gate part of the city's walled circuit.The concept of an isolated artillery tower was more common in France, where they were used as temporary and permanent defensive features during the Hundred Years War between the English and the French kings.The quatrefoil gunports in the lower levels could have been used for both hand cannons and crossbows, with overlapping fields of fire.