Tor di Caldano, Coastal tower in Anzio, Italy

Tor di Caldano is a circular stone tower positioned on a rocky promontory along the Mediterranean coast near Anzio. The structure rises from a rocky outgrowth over the water and marks an important point on the region's historical coastline.

The tower was built in the mid-17th century as a defensive structure to protect sulfur mines that operated from 1569 to 1828. During the Napoleonic Wars, it sustained damage from British naval bombardment.

The name Caldara comes from the sulfur "caldare" (cauldrons) of the mines worked here from 1569 until before 1828, which also gave the tower and the whole area their name. Visitors today walk the reserve's paths among the disused mining structures, sulfur springs and ponds, and can still see German bunkers and trenches left after the Allied landing of 22 January 1944.

The tower stands on a rocky promontory about five kilometres from the centre of Anzio, near Lavinio Lido di Enea, inside the 44-hectare Tor Caldara regional nature reserve. The reserve also holds the remains of a Roman villa, disused sulphur mine installations, sulphur springs, ponds and German bunkers and trenches from the 22 January 1944 landing. The cliff between Tor Caldara and Lido di Cincinnato/Tor Materno is rich in fossils, partly lost to erosion.

The site is noted for active sulfur springs that create yellow stains along the rocky shoreline and produce a distinctive mineral scent. These geochemical activities come from the same underground sources that miners exploited centuries earlier.