Comillas is a small township and municipality in the northern reaches of Spain, in the autonomous community of Cantabria. The Marquessate of Comillas, a fiefdom of Spanish nobility, holds ceremonial office in the seat of power at a small castle which overlooks the town. The Comillas Pontifical University was housed here before it moved to Madrid, and the old university buildings are among the finest examples of architecture in the town. Besides this, there are many notable medieval and baroque buildings.

From the second half of the 19th century, the Spanish royal family started spending their summers in Comillas, and so did large part of the Spanish nobility, whose many descendants still frequent the town every summer. As a result, Comillas left an imprint of architectural relics such as palaces and monuments designed by renowned Catalan artists in particular, i.e. Gaudí or Doménech i Montaner. From the second half of the 20th century however, southern Spain and the islands became more popular due to an increasing inclination towards sunnier destinations, and so places like Marbella, Sotogrande or Mallorca became attractive prospects for the rich and famous. Although the town has seen an upsurge in the last years, it still maintains its character as "the haven for the decadent and discreet aristocracy".

Comillas was the capital of Spain for a day, the 6 August 1881, following an agreement between king Alfonso XII and the Minister's Council to gather at a formal meeting in town. It also became the first place in Spain to use Edison's electric light bulbs, in 1880.