The+arch

Definition: a structure, especially one of masonry, forming the curved, pointed, or flat upper edge of an open space and supporting the weight above it, as in a bridge or doorway

History: it emerged after the post and lintel construction system and it allowed for higher and more stable buildings

Parts of an Arch:

The wedge-shaped blocks, called voussoirs, hold each other firmly in place and prevent each other from slipping. The voussoirs at the top, or crown, of the arch convert the downward pressure into lateral (sideways) pressure, or thrust, which is transmitted from the upper voussoirs down around the opening and finally into the ground through the wall or pier on which the arch rests. Not only can considerable distances be spanned in this way, but arches can carry a much heavier load than a horizontal lintel.

Examples:

-The Gateway Arch in Saint Louis, Missouri; a sculpture based on a catenary arch -The Arc de Triomphe, Paris; a 19th-century triumphal arch modeled on the classical Roman design -Arch of Constantine, Rome, Italy commemorating a victory by Constantine I in 312 AD