The Christ's Crypt
The Christ’s Crypt was built in the 13th century in a pure Gothic style. This is the oldest building in Santander. It can be reached through a vaulted porch in which two doors lay open. The main door is a pointed arch with archivolts supported by austere capitals with plant motifs. The other door is rarely used and was hidden for a long time.

The crypt, as such, is small and short -31 meters (102 feet) long and 18 meters (59 feet) wide, divided into three naves. Here the Saint Martyrs’ remains lie, an appropriate place since their first burial place was in the hermitage built beside the Roman governor's palace in Portus Victoriae. These ruins were discovered during the church's reconstruction works.

The silver Baroque-styled heads in which they were kept are now in the Diocesan Museum of Santillana. Besides these relics, a fragment of the Holy Cross and a relic from Saint Germain's arm are also kept in the Christ’s Crypt.