Villa del Priorato di Malta

Villa del Priorato di Malta, located on the Aventine Hill, is home to the Grand Priory in Rome of the Sovereign Military Order of Malta. Along with Palazzo Malta, the estate was granted extraterritorial status and remains a sovereign entity. It also hosts the embassy of the Order of Malta to Italy.

The site, on a rise directly overlooking the Tiber and access to the Roman Pons Sublicius, was already a fortified Benedictine monastery in the tenth century. The monastery passed to the Templars and after the destruction of their order, to the Knights Hospitallers, predecessors of the present Order of Malta. Radical rebuilding was undertaken in the 15th through 17th centuries. The villa was granted extraterritoriality in 1869. On the piano nobile is an assemblage of portraits of the Grand Masters of the Order.

The site is reached by via Santa Sabina, which ends in the small, picturesque piazza dei Cavallieri di Malta enclosed on two sides by the cypresses of the garden of the Benedictines backing the fantasy screen of obelisks and stele constructed in 1765 to designs by Giovanni Battista Piranesi, one of the very few executed designs by this etcher of Roman views who prided himself on being an architect. Ahead rises the Neo-Romanesque campanile of the Church of San Anselmo (1893-1900) attached to the international Benedictine seminary (Seminario Internazionale Benedittino). On the third, right-hand side is the monumental entrance screen, also designed by Piranesi under commission from Cardinal Carlo Rezzonico, nephew of Pope Clement XIII. The Villa is arguably best known for a small hole in the arch-headed central portone, through which the copper-green dome of Saint Peter's Basilica, the center of Roman Catholicism, can be viewed at the end of a garden allée framed in clipped cypresses (illustration).

...
Wikipedia