Parapet

A parapet is a barrier that is an upward extension of a wall at the edge of a roof,[1] terrace, balcony, walkway or other structure.

[2] Parapets were originally used to defend buildings from military attack, but today they are primarily used as guard rails, to conceal rooftop equipment, reduce wind loads on the roof,[3] and to prevent the spread of fires.

Built onto the side of Sigiriya Rock it ran for a distance of approximately 250 meters (270 yards) and provided protection from inclement weather.

This dates from the Building Act 1707 which banned projecting wooden eaves in the cities of Westminster and London as a fire risk.

[5] In the Bible the Hebrews are obligated to build a parapet on the roof of their houses to prevent people falling (Deuteronomy 22:8).