突堞

In architecture, a machicolation () is an opening between the supporting corbels of a battlement through which defenders can target attackers who have reached the base of the defensive wall. A smaller related structure that only protects key points of a fortification is referred to as a bretèche. Machicolation, hoarding, bretèches, and murder holes are all similar defensive features serving the same purpose: to enable defenders atop a defensive structure to target attackers below. The primary benefit of the design is to allow defenders to remain behind cover rather than being exposed when lean