The Altieri palace in Oriolo Romano was built over the years 1578-1585 by the will of Giorgio III Santacroce. Tradition attributes the design of the building as well as the entire urban framework to Jacopo Barozzi known as Vignola, but it is a very doubtful attribution. The palace reached its current configuration in 700 by the Altieri under the direction of Carlo Fontana. The two north-facing wings were added to the external bodies, so as to create a large courtyard. The furniture of the building is largely lost, what currently remains is original from the 17th century. The museum is divided into 14 rooms, arranged to the right and left of the Salone degli Avi, the fulcrum of the building, the S. Massimo Chapel work of the Orsini, and the Gallery of the Popes. Among the frescoes on the walls there is a precious image of the building before the interventions made by the Orsini and the Altieri. The dining room features late-eighteenth-century paintings depicting the surrounding feuds, the palace and via Altieri di Oriolo Romano. Of the collections present in the Museum, the most original and of considerable importance is the Gallery of the Popes commissioned by Clement X, which includes portraits depicting the popes who have followed one another in the history of the Church. The collection is particularly important as it is the only complete one of all the series of papal portraits. The long gallery develops in a sequence of nine rooms, most of the portraits, in total 268, were made before the end of the seventeenth century. The portrait of many of the popes of the sixteenth and seventeenth centuries is copied from examples made by famous artists: Julius II is a copy by Raphael, Palo III by Titian, Paolo V by Caravaggio. The arrangement of the paintings is in chronological order: St. Peter is placed in the first row at the top right of those entering the door, while the most recent in the row at the bottom left. In a stately home, the garden could not be missing to give the complete connotation of a patrician villa according to the stylistic canons of the sixteenth century. It is currently owned by the municipality.