The Astronomical Observatory of Rome (Osservatorio Astronomico di Roma in Italian) is one of twelve Astronomical Observatories in Italy. The main site of the Observatory is Monte Porzio Catone. Part of the Istituto Nazionale di Astrofisica since 2002. Monte Mario Monte Mario Observatory (IAU code 034), the "historical" Observatory of Rome, located at 84 via del Parco Mellini in the northwest part of the city, atop Monte Mario, since 2002 is only the administrative seat of the Istituto Nazionale di Astrofisica (INAF). Nevertheless, the Astronomical Observatory of Roma has the responsibility for the Astronomical Copernican Museum and the Solar Tower in Monte Mario. Monte Porzio Catone Monte Porzio Catone is located approximately 20 kilometres southeast of Rome proper. The Astronomical Observatory of Rome (OAR) was established in 1938, inside the 19th-century Villa Mellini on the hill of Monte Mario in Rome. In the same period, a new Observatory was built in Monteporzio Catone, in order to host a large telescope. With the Second World War, this project failed. In 1948, the building of Monteporzio was assigned to the Astronomical Observatory of Roma. In 1965, a new observing station was built in Campo Imperatore (2200 metres above sea level), on the Gran Sasso mountain. In 2017, the management of this station was transferred to the newly-established Osservatorio D’Abruzzo. Since 1988, the researchers of the Astronomical Observatory of Rome have been carrying out their research activity in Monteporzio Catone. The seat of Monteporzio includes the main building (three floors), the guesthouse, two small hoses for the janitors, AstroLAB, LightLAB, and the Monteporzio Telescope (MPT). These three latter structures are entirely devoted to public outreach. A few areas inside the main building are also occasionally used for visitors, i.e. historical rooms, “Livio Gratton” conference room, the modern library inside the main dome. The total area occupied by the structure within the compound sum up to about 8,750 square metres. Together with the garden, it adds up to about 75,000 square metres. OAR is responsible for the management of the “Museo Astronomico e Copernicano” (Astronomical Copernican Museum – MAC), in the ground floor of Villa Mellini. MAC was established in 1873 by Arthur Wolynski, upon the basis of a Copernican collection, put together on the occasion of the fourth centenary of the birth of Copernicus. This collection was implemented over the years with scientific instruments and historical books belonging to the older Observatories in