How Orvieto was built and evolved over time

Built of the thing it stands on

Orvieto is constructed from tuff quarried out of the rock beneath it, which produces a town of a single colour and, simultaneously, a hollow foundation. The two facts are the same fact: every block above ground is a void below it. Over three thousand years that has produced an extensive subterranean system — Etruscan wells, medieval cisterns, quarry chambers, olive presses, wine cellars and dovecotes — which is as much a part of the built town as the streets.

The cathedral, and the facade

The Duomo's foundation stone was laid on 14 November 1290, and from 1310 Lorenzo Maitani directed the work and gave the building its character. The facade is the point: horizontal bands of light and dark stone, deep carved relief at eye level, and large mosaic panels above, the whole thing composed to be read in direct sunlight.

That design decision explains something a visitor notices immediately — the cathedral looks like a different building on a bright morning and on a grey afternoon. A mosaic facade is a gamble on the weather, and in central Italy it is a reasonable one.

The two chapels

The Cappella del Corporale, built in the mid-fourteenth century, is the reason the cathedral exists: it was constructed to hold the Sacro Lino, the relic of the 1263 miracle of Bolsena. The Cappella di San Brizio opposite holds the fresco cycle begun by Fra Angelico in 1447 and finished by Luca Signorelli in 1499–1504.

The well, which is the best engineering in Umbria

The Pozzo di San Patrizio was commissioned by Pope Clement VII after the Sack of Rome in 1527 and completed in 1537 under Paul III. It is a shaft 62 metres deep and 13 metres wide, lit by windows cut through to the central void, with two helical staircases wound around it that never intersect.

The double helix is the whole idea and it is a logistics solution rather than an ornament: mules carrying empty vessels descend one stair while mules carrying full ones climb the other, and the two streams never meet or obstruct each other. It is a piece of Renaissance engineering of real sophistication, built for the single purpose of getting water inside a besieged rock.

Why the medieval town survives

Because the money left. Orvieto held around 30,000 people in the late thirteenth century and about 19,200 now, and a town that shrinks does not demolish. The same pattern as Siena, for the same reason, with the same result.