In 1199 a certain Rinaldo del Veccio fought for Viterbo against the Romans; but probably the name Roccalvecce came from the legume veccio or veccia, that was very common in the countryside. Rinaldo del Veccio could have been the castellano of Veccio or the Rocca del Veccio.
In 1210 the Cronache Viterbese narrate that Emperor Ottone IV invaded the castle of Rocca del Veccio; the Viterbesi defeated the emperor and took over the Rocca.
Numerous signori took turns in the possession of Roccalvecce: Ildebrando da Paregnano, Corrado and Ugolino di Uffreduccio who put the castle under the dominion of the City of Viterbo in 1254; a certain Ponzio who helped the Filippeschi to throw the Monaldeschi out of Bagnorea (Bagnoregio) in 1303 and Andreuccio di Fuccio.
In 1455 Pope Callistus III gave Roccalvecce to Guglielmo Gatti of Viterbo . Two coat-of-arms of this family can still be seen on the palace façade. It was in this period that the fortress was transformed into a castle.
In 1496 master of Roccalvecce, Giovanni Gatti, was killed by the Viterbesi along with his sons . His three daughters married a Baglioni (of Bologna), a Chigi and a Colonna from Rome and the castle and feudal property was inherited by the Baglioni and the Chigi families.
In the beginning of the 1600’s the Baglioni sold their properties and the castle to the Marchese Prsopero Costaguti, a Roman-Genoese patrician. In 1685 a sixth of the castle still belonging to the Chigi was bought by Marchese Giovan Battista Costaguti who enlarged it. In the meantime the parish church was restored by Cardinal Vincenzo Costaguti and donated to the parish.
In 1809 Marhcese Luigi Costaguti enlarged the palace adding on a second floor; in 1883 his grandson (nephew) Ascanio, further enlarged it, extending it to the parish church and constructing a third floor.
The last restoration ,begun in 1998, was carried out by Marchese Ferdinando Afan de Rivera Costaguti, son of Ascanio’s daughter and by the heirs of his brother Francesco.