An archivolt (or voussure) is an ornamental molding or band following the curve on the underside of an arch. It is composed of bands of ornamental moldings (or other architectural elements) surrounding an arched opening, corresponding to the architrave in the case of a rectangular opening. The word is sometimes used to refer to the under-side or inner curve of the arch itself (more properly, the intrados).

Characteristics
The archivolts solve the aesthetic problem presented by the openings in a thick wall, avoiding the tunnel sensation that they can generate. It is common to be adorned with reliefs, as its use is extended. Initially geometric decorations were made in the shape of sawtooth, chessed or dice, to later pass to plant elements and finally decorated with sculptural elements of half package (Saints, Apostles, etc.). The Portico de la Gloria of the Cathedral of Santiago de Compostela is a magnificent example of archivolts.

Word origin
The word originates in the Italian (or French) equivalents of the English words arch and vault.

Description
This series of volumetric bands concentrically traverses the inner zone of the arc, located in the gap, just above the opening. The strips progressively collect into the interior in grooves or steps supported by a sequence of flat supports or narrow columns embedded in the sides of the entrance vane. In the case of a rectangular opening, it is referred to as an architrave, a horizontal element above the opening.

Romanesque
During the Romanesque period the archivolts are guided by a Roman arch (or perfect back arch) and generally appear as ornate bands of circular profile (see image of the Cathedral of Espira).

Gothic
Already in Gothic the archivolts run through a broken arch (or warhead) and are decorated by a profusion of figurative sculptures that are closely related to the relief stories of the tympanum (see image of the Cathedral of Freiberga with formal organization of transition to Gothic).

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