Which architectural style is the Colegiata in Santillana del Mar, Spain?

Santillana del Mar is a historic town situated in Cantabria, Spain. The name actually derives from Santa Juliana (or Santa Illana) whose remains are kept in the Colegiata, a Romanesque church and former Benedictine monastery.

Romanesque architecture is known for its massive quality, thick walls, round arches, sturdy pillars, barrel vaults, large towers and decorative arcading. Each building has clearly defined forms, frequently of very regular, symmetrical plan; the overall appearance is one of simplicity

The church has its origins in a monastery dating from 870. Over the course of the 11th century it was transformed into a collegiate church, although the building visible today dates from the 12th century. It has three naves, with dome, transept, three semi-circular apses and a tower. The transept and apses conserve their original barrel-vaulted ceilings. Special mention should be made of the sculptural decoration of the doorway, the capitals and the cloister. Inside you can see medieval tombs and Romanesque reliefs from the 11th and 12th centuries. The main altar has an embossed silver front dating from the 17th century. Beneath this is another, in Romanesque style.