To admire the wonders of limestone concretions, you don’t have to be an experienced speleologist ready to explore inaccessible depths. In Bergamo, just cross the threshold of the Cannoniera di San Michele, a fascinating place that hides an unexpected geological treasure.
Once past the imposing St. Augustine’s Gate, on the right side of the avenue that runs along the majestic Venetian Walls, a discreet, almost hidden entrance opens up, leading gently into the belly of the earth. It is the entrance to the St. Michael’s Casemate, a historic site of great significance transformed over the centuries into a natural wonder.
History of Cannoniera di San Michele
Originally, this underground space played a crucial strategic role in the defense of the city. The casemate was used for the “flanked defense” of Porta Sant’Agostino and the bastion of the same name, an ideal position to protect the main access to the upper city. Built in the 16th century, the casemate was designed to house cannons and ammunition, ready to repel any enemy attack.
However, the fate of this place has taken an unexpected turn. Over the centuries, water has relentlessly penetrated through the cracks in the vault, eroding the rock and enriching it with minerals. This slow but inexorable process has resulted in a unique spectacle: the formation of stalactites and stalagmites.
Underground Geological Wonders
Inside the cannon house, the space originally occupied by cannons and ammunition has been gradually colonized by countless threadlike stalactites and small stalagmites. These limestone formations, created by the slow deposition of calcium carbonate, hang from the ceiling and rise from the floor, creating an atmospheric and surreal environment.
What makes this phenomenon even more extraordinary is the speed with which it occurred. While normally stalactites and stalagmites take millennia to reach considerable size, here the process was greatly accelerated. In “only” five centuries, some stalactites have reached lengths of up to three meters, creating a breathtaking visual effect.
The Charm of Stalactites and Stalagmites
The reason for this accelerated growth lies in the large amount of lime used by the builders to seal the vault stones. As it dissolved due to water infiltration, the lime released high concentrations of calcium carbonate, accelerating the process of concretion formation.
Today, the Cannoniera di San Michele (St. Michael’s Casemate) is a fascinating example of how nature can transform an artificial work into something unique and spectacular. Stalactites and stalagmites create a magical and evocative atmosphere, transporting visitors to an underground world of extraordinary beauty.