Tempio di Apollo (Lago d'Averno)

The so-called Temple of Apollo stands on the eastern shore of Lake Averno. It is not a temple but a large Roman thermal complex, whose octagonal hall and concrete construction reflect the exploitation of the area's volcanic heat.

Why it matters

The monument shows the scale of Roman bathing architecture outside the capital. Its thermal buildings drew on hot springs along the shore, while the name Temple of Apollo preserves a later humanist interpretation of the ruin.

What to notice

The second-century CE octagonal hall is the complex's defining structure. Its brick-faced concrete walls once supported a large roof, likely a dome. A circular basin stood at its centre, and a nearby circular room, 7.8 metres across, has a central opening known as a lumen. An earlier structure in opus reticulatum, dating to the first century BCE, was built to capture thermal vapours. Most of the original stucco and painted decoration has disappeared.

Context and history

The site developed around thermal springs on Lake Averno's eastern shore. Vapour-capture structures date to the first century BCE, followed by a monumental bath complex in the first century CE and the octagonal hall in the second century. Bradyseismic subsidence partly buried the structure. Renaissance scholars named the ruin for Apollo, linking the god to the Cumaean Sibyl across the lake; the historic name remains in use despite the building's identification as a bath complex.