Castroviejo is a village and municipality in the province and autonomous community of La Rioja, in northern Spain. It lies within the Ebro Valley region of La Rioja, a small autonomous community in the country's north.
The municipality covers an area of 20.75 square kilometres (8.01 square miles). As of 2011, it had a population of 67 people, making it one of the many sparsely populated rural settlements characteristic of the La Rioja countryside.