pendentivos

Pendentivos, in English known as pendentives, are architectural elements that provide a smooth transition from a square or rectangular base to a circular dome. They are formed by four curvilinear triangular zones that span from the corners of the supporting structure to the circular base of the dome. Together, they transfer the weight of the dome to the supporting piers or walls, allowing the dome to rest over a square plan.

In construction, each pendentive is bounded by concave surfaces created by the intersection of the dome with the arches forming the square. The geometry creates a transition from the square footprint to a circular dome without the need for a drum spanning the corners. Pendentives can be built in brick, stone, or modern materials and are often finished with plaster, mosaic, or other decoration.

Historically, pendentives appeared in late antiquity and became a defining feature of Byzantine architecture. The Hagia Sophia in Constantinople (532 CE) is a canonical example, where a massive central dome is supported on pendentives. The concept was later adopted and adapted in Islamic architecture and was revived in Western Europe during the Renaissance, influencing the design of many domed churches and mosques. Pendentives enabled larger, more open interiors and greater light by allowing expansive domes to be placed over square or rectangular spaces.