A murder hole or meurtrière is a hole in the ceiling of a gateway or passageway in a fortification through which the defenders could shoot, throw or pour harmful substances or objects such as rocks, arrows, scalding water, hot sand, quicklime, or boiling oil, down on attackers.
Their supposed intention was to discourage (or kill) invaders once they had breached the walls, though it has been suggested that they may have in some cases also facilitated more prosaic activities, such as communication between levels.
[citation needed] For example, the murder hole at Audley's Castle in County Down, Northern Ireland is located not over the main threshold, but over the entry way to an interior room.
[citation needed] However, murder holes have been described in a variety of areas within fortified buildings, and there is no completely reliable formula for their placement.
The murder hole in Tully Castle, County Fermanagh, Northern Ireland is located in the central portion of the first floor of the house, west of a cross-wall and piercing the vault of the lower chamber.