Castle of Monterroso Monument · Monterroso, Ulloa, Lugo Image of Monterroso, not of the place itself. The tower of Penas was known as the castle of Monterroso and at the beginning of the 12th century it became caught up in the dynastic conflict that set Alfonso the Battler against Queen Urraca and the party of Pedro Froilaz de Traba. Photo: P.Lameiro (CC BY-SA 3.0) What to see and do in Monterroso