Basilica of Saint Martin de Mondoñedo, Romanesque basilica in Foz, Spain

The Basilica of Saint Martin de Mondoñedo is a church of tan and grey stone blocks with a basilical plan of three naves and three semicircular apses. The central apse is divided by three vertical bands with windows and Lombard bands and blind arches. Two tall sloping stone buttresses project from the right half, and a low stone wall with a wooden fence stands in front.

In 866, bishops from Dumio relocated their seat to this location after Muslim invasions threatened their original city. This move established the site as a major religious center in the Kingdom of Galicia for centuries.

The basilica remains the parish church of San Martiño de Mondoñedo and holds the Museo Parroquial, where the tomb and gold pastoral ring of Bishop Gonzalo (bishop 1071–1112) are kept; the ring has a quartz stone set among four bird heads with brilliants in their eyes. Beside the church stands the Fonte da Zapata, where, by legend, the bishop threw a sandal and water sprang up, considered miraculous.

The site is located near the Cantabrian Sea and open to visitors during regular hours. An on-site museum displays religious artifacts and decorative pieces from different periods.

In 2008, restoration work on the south vault revealed a set of 12th-century wall paintings. Professor Manuel Castiñeiras attributes them to Bernardo, treasurer of Diego Xelmírez and illuminator of the Compostela Tombo A. They are not frescoes hidden in the stone walls but paintings on the vault.