A parapet, like this one on an apartment building in the 1500 block of College Avenue, is that part of the wall which rises above the roofline of the building. This parapet is purely decorative, but they were originally used as defensive features, offering shelter against enemy attacks and positions from behind which defenders could launch their rocks, or shoot their arrows guns or cannons.
Parapets were often found on English castles. Those castles and other fine English homes inspired the Tudor Revival style in the United States. The style became particularly popular in the years following World War I. Soldiers returning from service overseas brought an appreciation for the English architecture they’d seen home with them. Architects and builders created a trend, designing a multitude of residences and other buildings in Tudor Revival style in the years between the two World Wars.