Monastero Esarchico di Santa Maria di Grottaferrata

You're standing at the Abbey of Santa Maria di Grottaferrata, about twenty kilometres southeast of Rome. Start with the thick walls around the monastery. They look more like a fortress than a place of prayer, and that's no accident. Cardinal Giulio della Rovere, who later became Pope Julius II, was abbot here for a while. He built a castle and ringed the abbey with fortified walls. They're still standing today.