The Toledan rig (also known as masonry boxes or Mindonian rig)[1]​ is a construction system that appears in various towns in Castile (Spain).[2]​ It consists of a "Rig (construction)") made by a mixed brick and stone "Factory (construction)" factory. It is composed of masonry boxes between courses of brick (verdugadas) with "chains" of the latter at the limits of the facing. It is used on the walls of the exterior facades of medieval houses.

This type of factory is developed from the Roman rigs called opus mixtum and opus vittatum. Its presence occurs in late Roman works such as high and late medieval ones.[3] Being an evolution of Hispanic Roman architecture that was maintained in Muslim military architecture and later in the work of the builders in Mudejar Architecture in Toledo. From the century to the century it was a common denominator in the popular architecture of the Kingdom of Castile.[4]​ Being abandoned for centuries, the architect Luis Bellido y González put it back in fashion in the middle of the century in the restorations of the Plaza de la Villa "Plaza de la Villa (Madrid)"),[5]​ and in some modern buildings such as the Matadero in Madrid. The Catalan architect Gaudí also popularized it in some of his examples of modernist architecture.[6]​.

The facings "Facing (architecture)") of the homes that have this rig are characterized by the use of courses of brick combined with masonry boxes (generally flint is used).[2]​ The boxes or courses of masonry mean that there are various Toledo rigs, depending on the number of brick courses, the stones used in the masonry, etc.[7]​ It was common that the stone "drawers" were decorated with whitewashed plaster, leaving the rows of brick exposed. Nowadays, since the beginning of the century, it is common for walls, after being repaired and rehabilitated, to leave the brick exposed.

The use of the Toledo rigging allows the walls to resist the structural stress induced by diurnal temperature changes. This is due to the mixed use of two materials that compensate for thermal expansion by having different thermal responses.