Castel Gandolfo sites open for Castelli da scoprire! on 4 October
Published on 09/27/2026 at 15:43 | Editorial responsibility: Rafael Müller, Editor-in-Chief AD HOC NEWS
Castel Gandolfo and the Castelli da scoprire! programme will open the Apostolic Palace and Vatican Observatory to visitors on 4 October 2026. The event takes place in Castel Gandolfo, Italy, with access arranged at the palace ticket office in Piazza della Libertà.
The programme brings together two parts of the papal estate that offer different perspectives on the site. The palace presents the historic papal residence, while the Observatory connects Castel Gandolfo with the Vatican’s long scientific tradition.
Castelli da scoprire! opens the papal estate on 4 October
The announced event is an opening to the public of the Apostolic Palace and Specola Vaticana, the Italian name for the Vatican Observatory. The organiser lists the Apostolic Palace ticket office at Piazza della Libertà as the venue and gives 4 October 2026 as the event date.
Visitors will be able to explore the palace areas included in the programme and the museum spaces associated with the Observatory. The Observatory material includes historical instruments, astronomical displays, meteorite samples and views of the papal connection to the institution. The 4 October opening programme also states that reservations are required and that some Observatory visits are organised for groups.
Castel Gandolfo links a papal residence with astronomy
The Vatican Observatory is a scientific research institute directly dependent on the Holy See. Its origins reach back to 1578, when Pope Gregory XIII established a commission connected with the reform of the calendar promulgated in 1582.
Increasing electric light in Rome made astronomical work more difficult, so Pope Pius XI ordered the Observatory to move to his summer residence at Castel Gandolfo. The new site was established in 1935 with telescopes and an astrophysics laboratory. The Vatican Observatory history records the later creation of a second research centre in Tucson in 1981.
The astronomical domes remain a direct link between the event and the place. The Vatican State describes a major dome with a diameter of 8.5 metres and a smaller dome measuring 8 metres. Their instruments represent the working history of the Observatory, while the palace provides the architectural and political setting in which that history developed.
Visiting Castel Gandolfo: what travellers from Western Europe should know
- The public opening takes place on 4 October 2026 at the Apostolic Palace ticket office in Piazza della Libertà, Castel Gandolfo.
- The programme covers the Apostolic Palace and Vatican Observatory, with reservations required for the announced visits.
- The Observatory visit is historical and museum-based rather than a scientific observing session. The organiser states that the Observatory route is not currently accessible to wheelchair users or people with walking difficulties.
- The Observatory’s major dome measures 8.5 metres across and the smaller dome measures 8 metres, making the domes a specific feature of the visit.
- Castel Gandolfo is in Italy, where Italian is the official language and the euro is the national currency.
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Frequently asked questions about Castel Gandolfo
When does Castelli da scoprire! take place at Castel Gandolfo?
The public opening of the Apostolic Palace and Vatican Observatory is scheduled for 4 October 2026.
What is the Vatican Observatory at Castel Gandolfo?
It is a scientific research institute of the Holy See, transferred to Castel Gandolfo in 1935 and housed in part in historic astronomical domes.
Where is Castel Gandolfo and how do you get there?
Castel Gandolfo is in Italy, south of Rome. The event venue is the Apostolic Palace ticket office in Piazza della Libertà.
