La Puebla de Arganzón

The town has roots going back to at least 871, when an older settlement called Arganzón is recorded. That earlier nucleus disappeared around the middle of the medieval period, and La Puebla de Arganzón was founded in its place toward the end of the 12th century, during a period of frontier conflict between Castile and Navarre. It received its town charter in 1191 — sources disagree on whether this was granted by the Navarrese king Sancho the Wise or by the Castilian king Alfonso VIII.

When Spain's current provincial boundaries were drawn in 1833, the town was placed in the province of Burgos.

The entire town was declared a protected historic ensemble in March 2007. The walls came first, and the town plan was built to fit inside them — not the other way round. The street layout is unusually regular: one main longitudinal axis running the length of the town, with two parallel streets on either side and two cross streets cutting through.

The walls originally had four gates. Two survive: one to the north and one to the south. A third gate controlled the bridge over the river Zadorra, the most defensible point in the town and its refuge in times of attack. The fourth, known as the Arco de Santa María after the nearby parish church, stood at the far end of the bridge street but was demolished in more recent times to widen the road out of town.

A round medieval tower also survives in the northwest corner of the walls, sitting on a broader base than the tower itself.

The walls and gates once served a practical financial purpose too: the tolls collected at each entrance went toward maintaining the bridges over the Zadorra. The walls were separately declared a protected monument in June 1991.