Monzón de Campos Castle was built in the 14th century by the Rojas family on the remains of an earlier castle which was contemporary one. The keep, made of high quality ashlar masonry, has no openings besides a couple of small arrow slits which gives it a severe appearance.
The oldest part is the elevated entrance of the present tower of homage.The coat of arms on the pointed arch of the main gate belongs to the Rojas family.
Inside, the castle has not preserved the original distribution except in the tower. A Romanesque door was added to the tower of homage. It was brought in from a church that had been covered by the water of the dam in Aguilar de Campoo. The village of Monzón, with its castle, was the centre of a county donated to the Ansúrez family by the kings of León during the 10th and 11th centuries and in the 15th and 16th centuries it was owned by the Rojas, a family from Burgos that since 1530 had the title of Marquises of Poza. They are likely to have built the present castle in Monzón de Campos.
References:The Broch of Gurness is an Iron Age broch village. Settlement here began sometime between 500 and 200 BC. At the centre of the settlement is a stone tower or broch, which once probably reached a height of around 10 metres. Its interior is divided into sections by upright slabs. The tower features two skins of drystone walls, with stone-floored galleries in between. These are accessed by steps. Stone ledges suggest that there was once an upper storey with a timber floor. The roof would have been thatched, surrounded by a wall walk linked by stairs to the ground floor. The broch features two hearths and a subterranean stone cistern with steps leading down into it. It is thought to have some religious significance, relating to an Iron Age cult of the underground.
The remains of the central tower are up to 3.6 metres high, and the stone walls are up to 4.1 metres thick.