Santillana del Mar grew around a religious community in the green coastal hills of Cantabria. Tradition associates its origins with the relics of Saint Juliana, brought to the region during the early Middle Ages, though the precise sequence is uncertain. A monastery documented by the ninth century became the focus of settlement and landholding. The town’s name evolved from Sancta Iuliana, while its later addition del Mar reflects the wider coastal jurisdiction rather than a position directly on the shore. Farms and villages supported the ecclesiastical center.

Royal privileges strengthened the monastery, and by the twelfth century it had become a collegiate church served by canons. The surviving Colegiata de Santa Juliana is one of Cantabria’s major Romanesque monuments, with a sculpted portal, cloister capitals, church, tower, and dependencies built and altered across generations. Roads through northern Spain brought pilgrims, clerics, merchants, and officials. Houses gathered along streets between the collegiate precinct and the civic square, creating a compact urban form shaped by religious authority, local markets, and regional noble families.

Secular power grew as the Mendoza family and its descendants, the marquises of Santillana, gained influence from the later Middle Ages. Towers and fortified residences gave way to palaces and manor houses with arcades, coats of arms, balconies, courtyards, and service yards. The Torre de Merino, Torre de Don Borja, Casa de los Villa, and other buildings record competing jurisdictions and elite display. Artisans, farmers, servants, innkeepers, and clergy sustained the town behind these façades, while livestock and trade tied it to the Cantabrian countryside.

Santillana lost some political and economic importance as administrative centers and modern transport routes developed elsewhere. That relative marginalization helped preserve its stone streets and buildings, though they were never untouched. Nineteenth-century Romantic interest, heritage restoration, and the 1879 recognition of the nearby Altamira cave transformed the town into a cultural destination. Early restorers sometimes emphasized an ideal medieval appearance, while hotels, museums, and private residences adapted historic interiors. The result is a conserved ensemble shaped by both genuine continuity and modern decisions about picturesque authenticity.

Today the historic center remains inhabited and forms a gateway to Altamira and the northern Camino de Santiago. Conservation must balance residents, worship, traffic restrictions, building maintenance, and intense seasonal tourism. The town is often called the village of three lies because it is said to be neither holy, flat, nor on the sea, but the joke oversimplifies a complex past. Santillana’s value lies in the coherence of collegiate church, noble houses, lanes, squares, and rural setting, where medieval institutions and later heritage culture remain visibly intertwined.