The Greek Abbey of San Nilo, whose official name is the Esarchico Monastery of Santa Maria di Grottaferrata, is now the only Greek-Byzantine rite Abbey existing in Italy. Before this place became a Christian settlement, there was a Roman villa from the imperial age. The imposing remains of that villa are located below the level of the present church square. The Roman villa had in turn incorporated a pre-existing sepulchral cell of the Republican age closed by railings, the “crypta ferrata” which gave rise to the name Grottaferrata. Currently, the Greek Abbey of San Nilo is the last of the numerous Byzantine monasteries that in the Middle Ages were widespread throughout southern Italy and in Rome itself. It was founded in 1004 by a group of Greek monks from southern Italy, led by S. Nilo di Rossano, a charismatic leader and leading spiritual personality of his time. At the end of the fifteenth century the abbey complex was incorporated into a mighty circle of walls, designed by Antonio da Sangallo the Younger and Baccio Pontelli, at the behest of Cardinal Giuliano della Rovere, later Pope with the name of Julius II. Odoardo Farnese in 1610 enriched the ornamental part by commissioning Domenichino for the valuable frescoes that can be admired today.