How Subiaco was built and evolved over time

Subiaco is built on the slope of a hill, and the hierarchy of the buildings follows the slope exactly.

At the top is the Rocca Abbaziale, the fortress of the abbots, which still crowns the skyline and now holds the civic museum. Below it the medieval centre descends in tight lanes and stepped alleys, a core of about thirteen hundred residents inside a comune of eight and a half thousand. Below that again, twentieth-century blocks spread along the valley road.

The monasteries are built differently, because they are built on rock. Santa Scolastica is organised around three cloisters of three different centuries — a Cosmatesque one, a Gothic one and a Renaissance one — with a Romanesque bell tower, so the building reads as a sequence of rebuildings rather than a single design.

The Sacro Speco is the more extreme piece of construction: a sanctuary raised in the twelfth century directly over Benedict's cave and fixed to the cliff face above the gorge, its chapels stacked on each other because there is no flat ground to spread them across.

Everything below is Roman engineering. Nero's dams across the Aniene made the three lakes, and the largest of them stood as the highest dam in the world until 1305.