The "Grotte di Rescia" are natural grottos of tufa, a porous rock, on the lake of Lugano, near Porlezza. These grottos have been formed over the centuries by the action of water springs which contain a solution of calcium bicarbonate.
This calciferous water drips continuously, depositing a pastlike substances, called Calc-Tuff, on anything that it comes in contact with. This substance is insolubile in water, thus forming the stalactites which visitors to the grottos could see.
From the natural opening that exist in one of the grottos, you can enjoy the view of the waterfall of the S.Giulia torrent.