Discover the astronomical observatories of the Vatican Observatory of the Papal Palace of Castel Gandolfo.

Climb to the third floor of the palace and admire the view of Lake Castel Gandolfo from the panoramic terrace. For the first time in almost ninety years since their construction, the astronomical domes of the Papal Palace of Castel Gandolfo are opening their doors to visitors. These are two perfectly functioning astronomical observatories of the Vatican Observatory: the “major dome” with a diameter of 8.5 meters, equipped with a Visual Telescope, for observing stars and planets; and the “minor dome”, with a diameter of 8 meters, with the Double Astrograph, used for photographic surveys of the sky and the position of the stars. Access allows, via a spiral staircase, access to the third floor of the Papal Palace, on the highest point of the panoramic terrace, which offers a splendid view of the lake of Castel Gandolfo. It was Pius XI, on September 29, 1935, who inaugurated the new headquarters of the Vatican Observatory, as its transfer from the villa that Leo XIII had built in the Vatican Gardens became necessary due to the light pollution of the City.

The astronomical observatory was thus refounded and entrusted to the Jesuits, equipping the Observatory with three new telescopes and an astrophysical laboratory for spectrochemical analysis. Among the various study programs of the new institution, in those years, an important research on variable stars should be remembered.