Festivities of San Marcos de Castrotierra Activity · Castrotierra de Valmadrigal, Sahagún, León Image of Castrotierra de Valmadrigal, not of the place itself. On 25 April the village celebrates San Marcos, one of its two festivals along with that of San Pedro, and reserves the summer festivities for the first days of August, when the residents who emigrated come back. Photo: Rodelar (CC BY-SA 4.0) What to see and do in Castrotierra de Valmadrigal