Subiaco is a comune (municipality) in the Metropolitan City of Rome Capital, in the Italian region of Latium, 40 kilometres (25 mi) from Tivoli alongside the River Aniene. It is a tourist and religious resort because of its sacred grotto, in the medieval St. Benedict's Abbey, and its Abbey of Santa Scolastica. It is one of I Borghi più belli d'Italia. The first books to be printed in Italy were produced here in the late 15th century.

Lucius Caecilius Firmianus signo Lactantius was an early Christian author who became an advisor to Roman emperor Constantine I, guiding his Christian religious policy in its initial stages of emergence, and a tutor to his son Crispus. His most important work is the Institutiones Divinae, an apologetic treatise intended to establish the reasonableness and truth of Christianity to pagan critics.