Visits to the Vatican Observatory sites are constrained by our small staff and restricted quarters. Individual visits to the Observatory are not possible. 

Our telescope in Arizona is in a protected Forest Service area. Visits can be arranged through the Eastern Arizona College Discovery Park Campus: https://www.eac.edu/discoverypark/mgio.shtm

Our offices and telescopes in Castel Gandolfo are in the Papal summer gardens. The Vatican Museum hosts tours of the Gardens and the former Summer Palace 

https://www.museivaticani.va/content/museivaticani/it/organizza-visita/scegli-la-visita.html

At the moment these tours do not include visits to Specola sites; we are in the process of developing a Specola Visitor Center in conjunction with the Vatican Museums, and we hope to have this open to the public sometime in the coming year. Occasional visits by groups of 10-25 people can sometimes be arranged; enquire at staff@specola.va