The Cathedral of Santander is not your typical European cathedral.
It’s a complex of Gothic buildings built between the 12th and 18th centuries. It consists of two joined churches built on an incline on the hill of Somorrostro. The lower church is the oldest and recent excavations have uncovered baths and other artifacts from an ancient Roman settlement, all of which can be seen via a glass floor. One of the things that most struck my attention was the silver heads on one side of the cathedral. The real heads of the martyrs San Emeterio and Celedonio are said to be kept inside.
The upper church has been expanded several times and its ceilings are much higher and are supported by Gothic arches. It's all very austere in terms of decoration. It has two different bell towers and several chapels. You can also visit the cloister which, for me, was the most beautiful part.