The name 'Tenuta del Massimo Feudo' literally translated into English means 'Estate of the Marquis of Feudo'. This name was established by the Supreme Pontiff Benedict XIV in 1753 who had given the title of "Marquis of Castelmassimo" to Agostino Campanari. He owned the building and agricultural land around it in the countryside of Veroli. He was a descendant of the Campanari (bell ringers) family whose origins date back to 1110 and the family line goes back to Angelo Maria Campanari, Castellan of Rhodes, a veteran of the first crusade.
The building was built in the mid-1500s, incorporating the ancient bell tower of which sill remain original parts. In 1711 the adjoining church, dedicated to the apostles Peter and Paul and still open for worship, was built. The management of the church was sold by the Campanari family to the bishopric of Veroli.
The castle has been the scene of many historical events. It has hosted General Gioacchino Murat and the hero of two worlds Giuseppe Garabaldi to name a few. In 1943 the prefect of Frosinone had accommodated the battalions of the Piave Division in the estate building. By September 1943 the castle had become the seat of the Eighth Army under the command of the German general Fridolin von Senger und Etterling. In June 1944 it had become the seat of the English command under Supreme Allied Commander in the Mediterranean; Field Marshal Henry Maitland Wilson.