As explained in wikipedia (yep!), an A-frame is an architectural house style featuring steeply-angled sides (roofline) that usually begin at or near the foundation line, and meet at the top in the shape of the letter A. After Andrew Geller used this type of design to build a house in Long Island in 1955, A-frames become very popular in USA. They were specially used as vacation houses. Aren’t they just beautiful?