The pope’s summer palace, Castel Gandolfo has only recently been opened to garden lovers. The gardens are on the south-west shore of Lake Albano and built over the ruins of an ancient Roman villa, Albanum Domitiani. It has a grand belvedere, and a perfectly pruned Italian parterre. This is one of the very few gardens you can visit and admire in the pouring rain (a rare event south of Rome), thanks to a Roman cryptoporticus, or covered passageway. There is a magnificent magnolia collection and a model farm that grows produce for the pope’s table.