Parapet

A parapet is a wall-like barrier at the edge of a roof, terrace, balcony, or other structure. Where extending above a roof, it may simply be the portion of an exterior wall that continues above the line of the roof surface, or may be a continuation of a vertical feature beneath the roof such as a fire wall or party wall. Parapets were originally used to defend buildings from military attack, but today they are primarily used to prevent the spread of fires.