The Casino dei Principi took on its present 16th century appearance after restoration work carried out by Giovan Battista Caretti from 1835 to 1840, commissioned by Prince Alessandro Torlonia (1800-1886). The earliest nucleus of the Casino was a modest rural building in the Vigna Abati, which had already stood for about a century before Giuseppe Valadier (in approximately 1802 when he is known to be present in Villa Torlonia) probably began to work on it. The little building was used by Alessandro Torlonia during the lavish society events organized at the Villa as a separate addition to the main Palace to which it is connected by an underground gallery. The French windows on the raised piano nobile, which open onto the balcony that runs along the main façade, would have provided a magnificent view of the Villa and an excellent vantage point for performances in the Amphitheatre below (demolished in 1910 when Via Nomentana was widened). The exterior of the Casino presents several original decorative elements, including two marble portals with ancient columns situated on the minor facades; cast-iron vases decorating the attic and the principal facades; and what remains of the monochrome frieze of the Triumph of Alexander in Babylon. The three salons on the piano nobile were entirely covered in wall paintings featuring scenes from ancient Greece, ancient Rome and, in what was the dining room, the Gulf of Naples. The paintings, many of which have been lost, were the work of various artists coordinated by Giovan Battista Caretti.