First documented mention of Guardo Historical milestone · Guardo, Alto Carrión, Palencia Image of Guardo, not of the place itself. Guardo is mentioned in the tenth century as Buardo or Boardo, linked to the monastery of San Román de Entrepeñas; its castle watched over the border between León and Castile and the passage through the Carrión valley. siglo X Photo: Alejandro Polanco (CC BY 3.0) What to see and do in Guardo