·  The Overseers of New Gate prison have constructed a building over the Shaft that connects with the prison caverns.

·  The building is 40 feet long and 30 feet wide, surrounded by a 2-foot-thick stone wall.

·  The wall is made of hewn stones, laid side by side in two tiers, and bound together with iron cramps.

·  The wall is 7 feet high and built on a stone floor, divided into two rooms: the invalid room and the passage room.

·  A heavy iron gate has been placed at the mouth of the shaft for security.