The Hole of Lead is an imposing natural cave located in the municipality of Erba, in the Como Prealps at an altitude of 695 meter above sea level.

The cave is part of a karst complex formed in the limestone rock of the Mesozoic age near the locality called Alpe del Viceré located within the Valle Bova nature reserve.

It opens onto a vertical white wall with a gigantic opening: 45 meters high and 38 meters wide.

The gallery that can be visited is 300 meters long, the rest of the cave, accessible to speleologists, is a few kilometers long, forming a karst system consisting of the Buco del Piombo, Grotta Lino and Grotta Stretta caves extended for about 6,500 meters. Inside there are some concretionary phenomena of stalactites and stalagmites.

The human presence is documented since the Paleolithic period by the discovery of various lithic finds, and it was also inhabited by Neanderthal man.

The cave was the site of the extraction of silica stone for the production of tools, our ancestors probably did not live there continuously, due to the cold, humidity and the presence of hibernating cave bears.

The cave bear (Ursus spelaeus) was in fact the main inhabitant of this cave in the last glacial period (up to about 15,000 years ago), numerous bone remains of this animal have been found inside the cave.

The wall structures inside the large entrance hall to the cave have been dated to the mid-sixth century AD, based on the results of radio-carbon analyzes of some wooden fragments found inside one of the many holes bridges present in the rock and document a continuous human presence in the late Roman and medieval times, up to the sixteenth century.

The place was in fact used as a defensive fort in times of war. During the late Roman period it would have been part of a system of signaling towers which also included the fortifications of Lecco, Castelmarte, Baradello, Colle di San Maffeo and Castelseprio.

In modern times the cave has become the object of visits by scholars and tourists. Among the latter, Queen Margherita of Savoy should be remembered.

The access, which is located on private property, was then closed for many years until 1998 when an agreement with the municipality of Erba allowed its reopening. Various species of insects, crustaceans, flatworms and bats live in the dark, humid and cold environment.

In the past, during the Ice Age, the cave was frequented by the cave bear, of which many bone remains have been found, including some complete skeletons. Due to the gradual darkness, the vegetation is reduced as you continue towards the inside of the cave. In the entrance hall there is the yew and the stonebreaker Ceterach officinarum.

The first ten meters of the cave, still reached by sunlight, hosts various types of ferns, in fact these are plants that prefer humid places such as caves.