– ROMAN ARCHITECTURES –
The lake Albano is located in the Castelli Romani, on the Alban Hills in Rome, and with its depth of 170 meters is one of the deepest crater lakes.
A lovely stretch of water, dominated by the papal residence, located about three hundred meters above the sea level and that reaches a maximum width of 3500 meters and with a perimeter of 9800 meters.
During the terminal phase of the volcanic activity of the Latium’s volcanoes, the encounter between the masses of magma and the groundwater favored the formation of numerous lakes, such as Lake Albano and Lake Nemi that are the only ones left to date.
From thousands of years, the eruptive activity is still in a quiescent state, but it is still possible to record volcanic phenomena albeit modest, and emanations of carbon dioxide from the bottom of the lake, that cross the water in the form of bubbles.
Apart from its beauty in the setting of buildings and woods, this lake is remembered for the colossal work of hydraulic engineering of the so called “emissary”, which Romans built in 397 BC using techniques still unknown. The reason for this emissary is mainly due to avoid the flooding of the lake that could destroy the Emperors’ villas.
Instead, according to the historian Livy, this work of hydraulic engineering, particularly interesting for those times, would have been originated by a prophecy of the Delphic oracle:
At the time when the Romans besieged the inhabitants of Veii [in the days when the star Sirius was rising] in the season when the waters of the lakes are lowered, as is the case for all rivers except the Nile, and in a period when there is no rain or other causes perceptible to humans, the lake located on the Alban Hills, where the mother city of Rome rises up, had such a growth of waters to flood a large portion of the surrounding region, destroying many farms, cutting through the mountain and pouring a large river in the plains below. At first, Romans believed that a god was angry, and voted to propitiate gods and minor deities of the region, and then they asked to the soothsayers what they thought about this, but since they did not have anything to say, Romans decided to consult the oracle Delphi.
In the meantime, thanks to the Veii’s Etruscan soothsayers, the Romans who had besieged Veii, gained knowledge that, according to ancient prophecies, the victory of the Romans against Veii became feasible only when the lake’s water had channeled and used to irrigate the fields. After a short time, a messenger returned from Delphi with a similar response, a thing that pushed the Senate to dig canals to drive the overflowing warm waters of the lake.
Dion.Hal, Romanae Antiquities, XII, 10-12
And so it was; in no time the water reached the sea, at first thru a gallery of about 2500 meters, that appeared near the Via Appia in the locality “Quarto Mole” (below Castel Gandolfo), and then with another funnel that reached “Tor di Valle”, and from there into Tiber river. It has been a complicated manual labor of about 180 cm in height and 120 cm in width, with tunnels and vents that still could be useful in the event of a flooding.