Day trips from Bilbao

A small Burgos town that once sat on the front line between Franco's Nationalist territory and the Republican regions of Cantabria and the Basque Country.

Perched on a rock above the Ebro river in Burgos province, Frías crowns its crag with a medieval castle, two surviving town gates, and streets of timber-framed houses that still hang from the cliff face.

The administrative capital of the ancient Siete Merindades of Castilla la Vieja, Villarcayo holds Gothic tombs, a tent-shaped modernist church, and the second most important historical archive in the province of Burgos.

A walled hilltop town in Álava's Basque Country, its medieval streets and fortified walls rising above one of Spain's oldest pre-Roman Celtic settlements.

A fortified medieval town on the Bidasoa river in Gipuzkoa, its intact walls, Gothic-baroque church, and Carlos V castle standing where Castile and France have faced each other across the water for eight centuries.

Built around a medieval collegiate church holding the relics of a Galilean martyr, and neighbour to the Palaeolithic cave paintings of Altamira, Santillana del Mar is one of Cantabria's most complete historic towns.

A walled medieval town in Palencia where six of the original seven gates still stand, a Premonstratensian monastery anchors the old centre, and a hilltop castle overlooks the Pisuerga river.

Known as the cradle of Castile, this Arlanza-river village guards a rare 10th-century defensive tower and a timber-framed old town tied to Count Fernán González.

A long, thin town strung along a hillside under a ruined castle, and one of the quieter, more atmospheric stops on the Camino Francés.

A Benedictine monastery town famed for its two-storey Romanesque cloister and the Gregorian chant of its monks, set in the quiet hills south of Burgos.