The Blue Grotto is a well-known cave located in the municipality of Anacapri, on the island of Capri, the opening is partially submerged by the sea and, depending on the cycle of the tides or the climatic conditions, access can be more or less complicated. The Grotto was a sumptuous Nymphaeum, adorned with a rich sculptural decoration with a marine procession following Poseidon; at the bottom of the cave, in the emerged part, there are few remains of Roman cement work and, in the submerged part, there are niches that in ancient times housed the sculptures and some finds are still visible on the seabed. Some statues are currently on display in the Red House in Anacapri. Above the Grotto are the remains of one of the twelve Roman villas on the island of Capri that historical tradition attributes to the Emperor Tiberius. The typical bright blue color assumed by the waters and internal walls of the cave, which varies according to the time of day and weather conditions, is due to the reflection of sunlight filtered by the opening (larger in its submerged portion) on the sandy bottom of the grotto. It became known starting from 1826, when it was visited by the German artist August Kopisch on the recommendation of Angelo Ferraro, a local fisherman.