The keystone (shown in red) of an archDropped keystone at Colditz Castle
A keystone (or capstone) is the wedge-shaped stone at the apex of a masonry arch or typically round-shaped one at the apex of a vault. In both cases it is the final piece placed during construction and locks all the stones into position, allowing the arch or vault to bear weight.[1][2][3] In arches and vaults (such as quasi-domes) keystones are often enlarged beyond the structural requirements and decorated. A variant in domes and crowning vaults is a lantern. A portion of the arch surrounding the keystone is called a crown.[4]
Keystones or their suggested form are sometimes placed for decorative effect in the centre of the flat top of doors, recesses and windows, so as to form an upward projection of a lintel, as a hallmark of strength or good architecture.
Although a masonry arch or vault cannot be self-supporting until the keystone is placed, the keystone experiences the least stress of any of the voussoirs, due to its position at the apex.[citation needed] Old keystones can decay due to vibration, a condition known as bald arch.
Architecture
In a rib-vaulted ceiling, keystones commonly mark the intersections of any two or more arched ribs. For aesthetics, keystones are often larger than ribs in vaults and many of the voussoirs (arch stones) in arches, or embellished with a boss.
A "dropped keystone" is one where the keystone projects lower than the other voussoirs. Following Giulio Romano, Mannerist architects of the 16th century often designed arches with enlarged and slightly dropped keystones, as in the "church house" entrance portal at Colditz Castle. Numerous examples are found in the work of Sebastiano Serlio, a 16th-century Italian Mannerist architect.
Metaphor
Keystone is often used metaphorically for an essential part on which the whole depends or as an acme of the whole.
The U.S. state of Pennsylvania calls itself the "Keystone State", because during early American history, it held a crucial central position among the Thirteen Colonies geographically, economically, and politically, like the keystone in an arch.[5] A keystone is a symbol of Pennsylvania, being used in the logos of many Pennsylvania government departments, in Pennsylvania state route signs, and on Pennsylvania car license plates, and the Shoulder Sleeve Insignia of the Pennsylvania National Guard's 28th Infantry Division (United States), a Red Keystone, first adopted during World War I in October 1918.
In Christianity, Psalms 118:22,[6] translated in the Authorized Version as "The stone which the builders refused is become the head stone of the corner", is taken to refer to Jesus.
Referring to the Book of Mormon, Joseph Smith said that it "was the most correct of any book on earth, and the keystone of our religion, and a man would get nearer to God by abiding by its precepts, than by any other book."[7]Ezra Taft Benson, the 13th president of the Church of Jesus Christ of Latter-day Saints, said it "is my prayer that the Book of Mormon may become the keystone of our lives."[8]
Renaissance architecture is the European architecture of the period between the early 15th and early 16th centuries in different regions, demonstrating a conscious revival and development of certain elements of ancient Greek and Roman thought and material culture. Stylistically, Renaissance architecture followed Gothic architecture and was succeeded by Baroque architecture and neoclassical architecture. Developed first in Florence, with Filippo Brunelleschi as one of its innovators, the Renaissance style quickly spread to other Italian cities. The style was carried to other parts of Europe at different dates and with varying degrees of impact.
An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but structural load-bearing arches became popular only after their adoption by the Ancient Romans in the 4th century BC.
Romanesque architecture is an architectural style of medieval Europe that was predominant in the 11th and 12th centuries. The style eventually developed into the Gothic style with the shape of the arches providing a simple distinction: the Romanesque is characterized by semicircular arches, while the Gothic is marked by the pointed arches. The Romanesque emerged nearly simultaneously in multiple countries ; its examples can be found across the continent, making it the first pan-European architectural style since Imperial Roman architecture. Similarly to Gothic, the name of the style was transferred onto the contemporary Romanesque art.
Gothic architecture is an architectural style that was prevalent in Europe from the late 12th to the 16th century, during the High and Late Middle Ages, surviving into the 17th and 18th centuries in some areas. It evolved from Romanesque architecture and was succeeded by Renaissance architecture. It originated in the Île-de-France and Picardy regions of northern France. The style at the time was sometimes known as opus Francigenum ; the term Gothic was first applied contemptuously during the later Renaissance, by those ambitious to revive the architecture of classical antiquity.
A rib vault or ribbed vault is an architectural feature for covering a wide space, such as a church nave, composed of a framework of crossed or diagonal arched ribs. Variations were used in Roman architecture, Byzantine architecture, Islamic architecture, Romanesque architecture, and especially Gothic architecture. Thin stone panels fill the space between the ribs. This greatly reduced the weight and thus the outward thrust of the vault. The ribs transmit the load downward and outward to specific points, usually rows of columns or piers. This feature allowed architects of Gothic cathedrals to make higher and thinner walls and much larger windows.
Giulio Pippi, known as Giulio Romano and Jules Romain, was an Italian painter and architect. He was a pupil of Raphael, and his stylistic deviations from High Renaissance classicism help define the sixteenth-century style known as Mannerism. Giulio's drawings have long been treasured by collectors; contemporary prints of them engraved by Marcantonio Raimondi were a significant contribution to the spread of sixteenth-century Italian style throughout Europe.
Rustication is a range of masonry techniques used in classical architecture giving visible surfaces a finish texture that contrasts with smooth, squared-block masonry called ashlar. The visible face of each individual block is cut back around the edges to make its size and placing very clear. In addition the central part of the face of each block may be given a deliberately rough or patterned surface.
A voussoir is a wedge-shaped element, typically a stone, which is used in building an arch or vault.
This page is a glossary of architecture.
A corbel arch is an arch-like construction method that uses the architectural technique of corbeling to span a space or void in a structure, such as an entranceway in a wall or as the span of a bridge. A corbel vault uses this technique to support the superstructure of a building's roof.
In architecture, a boss is a decorative knob on a ceiling, wall or sculpture.
In Gothic architecture, a lierne is a tertiary rib connecting one rib to another, as opposed to connecting to a springer, or to the central boss. The resulting construction is called a lierne vault or stellar vault. The term lierne comes from the French lier.
The Monastery of Jesus is a historical religious building in Setúbal, Portugal, which served a monastery of Poor Clare nuns. It is one of the first buildings in the Manueline style, the Portuguese version of late Gothic. The cloisters of the complex houses a museum of the monastery. In 2013, pan-European heritage organization Europa Nostra declared the monastery to be one of the 7 most endangered monuments in Europe.
The Cathedral of St. Bartholomew, originally the Church of St. Bartholomew, is a Gothic church located on the Main Square in Plzeň, Czech Republic. It was probably established together with the city around the year 1295. The church became a cathedral in 1993, when the Plzeň diocese was created. It was designated a national cultural monument of the Czech Republic in 1995.
In architecture, a vault is a self-supporting arched form, usually of stone or brick, serving to cover a space with a ceiling or roof. As in building an arch, a temporary support is needed while rings of voussoirs are constructed and the rings placed in position. Until the topmost voussoir, the keystone, is positioned, the vault is not self-supporting. Where timber is easily obtained, this temporary support is provided by centering consisting of a framed truss with a semicircular or segmental head, which supports the voussoirs until the ring of the whole arch is completed.
English Gothic is an architectural style that flourished from the late 12th until the mid-17th century. The style was most prominently used in the construction of cathedrals and churches. Gothic architecture's defining features are pointed arches, rib vaults, buttresses, and extensive use of stained glass. Combined, these features allowed the creation of buildings of unprecedented height and grandeur, filled with light from large stained glass windows. Important examples include Westminster Abbey, Canterbury Cathedral and Salisbury Cathedral. The Gothic style endured in England much longer than in Continental Europe.
French Gothic architecture is an architectural style which emerged in France in 1140, and was dominant until the mid-16th century. The most notable examples are the great Gothic cathedrals of France, including Notre-Dame Cathedral, Reims Cathedral, Chartres Cathedral, and Amiens Cathedral. Its main characteristics are verticality, or height, and the use of the rib vault and flying buttresses and other architectural innovations to distribute the weight of the stone structures to supports on the outside, allowing unprecedented height and volume. The new techniques also permitted the addition of larger windows, including enormous stained glass windows, which fill the cathedrals with light.
Pendant vaulting is considered to be a type of English fan vaulting. The pendant vault is a rare form of vault, attributed to fifteenth century English Gothic architecture, in which large decorative pendants hang from the vault at a distance from the walls. In some cases, the pendants are a large form of boss. In his book on fan vaults, Walter Leedy defines the fan vault stating: “Fan vaults have the following specific interrelated visual and structural characteristics: (1) vaulting conoids of regular geometric form, (2) vertical ribs, each of consistent curvature and placement, (3) a distinct central spandrel panel, (4) ribs perpendicular to the vaulting surface, and (5) applied surface patterning.”
Romanesque architecture appeared in France at the end of the 10th century, with the development of feudal society and the rise and spread of monastic orders, particularly the Benedictines, which built many important abbeys and monasteries in the style. It continued to dominate religious architecture until the appearance of French Gothic architecture in the Île-de-France between about 1140 and 1150.
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