Keystone (architecture)

As a capstone, or apex stone of the wedge stone at the highest point ( apex ) of an arc or the final stone is referred to in the main junction of a rib vault. In the bow, the keystone is wedge-shaped in the vault on the other hand round, usually with rib attachments; it can also be formed as knob or a ring composed of several pieces. A special form is found in vaults, particularly in the late Gothic period the "hanging keystone " or hanging knob (see: Abhängling ).

In the vault of the capstone plays a crucial role: only if it is used, the structure is self-supporting, and the falsework may be removed. Due to its special meaning and its central position the keystone of arches was often decorated bauplastisch; been the keystone of the Porta all'Arco, the only well-preserved gate of the city walls of Volterra from the Etruscan period, wearing a head - sculpture on display. Frequently the keystone bears the initials of the builder and the year of the building. Rich decorations on the capstone of vaults were particularly common in Gothic architecture.

Keystone of the vaulted ceiling of Justin 's Church in Frankfurt -Höchst

Vault keystone of the central yoke with the image of Christ, 14th Century, Marienburg

Abhängling in Leonhard 's Church in Frankfurt -Altstadt