Question: Justo Perez Santiago was an abbot of what Monastery that has a memorial in the municipality of San Lorenzo de El Excorial? 
Sentence (from "Justo Pérez de Urbel"): Justo Pérez Santiago (August 7, 1895 – 1979) later known as Fray Justo Pérez de Urbel y Santiago O.S.B. was a Spanish Roman Catholic clergyman (Order of Saint Benedict) and medievalist, first abbot of the Monastery of the Holy Cross of the Valle de los Caídos, member of the Consejo Nacional del Movimiento (the first quasi-parliamentary assembly of Francoist Spain), later a Procurador en Cortes (member of the longer-lived Francoist assembly established after the end of the Spanish Civil War) and distinguished scholar of medieval Castile.
Relevant evidence: Yes