Rome eyes ancient underground tunnels as cool shelters for soaring summer heat

Rome’s municipal authorities are probing the capital’s extensive subterranean fabric—comprising ancient quarries, early-Christian catacombs, railway tunnels and World-War-II shelters—as a climate-adaptation tool to protect citizens from ever-more extreme summer temperatures. ISPRA, in partnership with the National Research Council and the University of Tuscia, has mapped thousands of cavities across more than 100 km², many of which maintain stable temperatures between 10 °C and 17 °C at roughly 3.5 m depth.

Geologist Francesco La Vigna explains that these naturally cool zones could serve as free public refuges, provided that ceiling and wall stability, humidity control and ventilation to mitigate radon are ensured. City Climate Change Office director Edoardo Zanchini stresses that safety and free access are non-negotiable, and the underground sites would augment an existing network of 178 indoor climate shelters and over 400 outdoor cooling areas.

The scheme forms part of a €50 million five-year Heat Plan that also expands shade, vegetation and reduces paved surfaces. Rome hopes the model can inspire other Mediterranean cities confronting similar heat challenges.