The monument of the Piramide is an ossuary sited in the Parco della Rimembranza, the park created in 1923 in memory of the people of Bagnoregio who fell in the First World War. Trees were planted to honor each of them. In October 1867, a three-day bloody firefight involving Garibaldian volunteers and Pontifical troops took place in this area and in the nearby territories causing deaths and injuries. This battle has gone down in history as the Battaglia di Bagnorea and ended with the victory of the Papal army. In 1878, the Associazione dei Reduci delle Patrie Battaglie di Viterbo took the initiative for the construction of an ossuary-pyramid dedicated to the Garibaldians killed in battle on 5 October 1867. The memorial was inaugurated in 1891.