Lake Albano in Roman myths.

Lake Albano is a small volcanic crater lake in the Alban Hills of Lazio, at the foot of Monte Cavo, 20 km (12 miles) southeast of Rome. Castel Gandolfo, overlooking the lake, is the site of the Papal Palace of Castel Gandolfo.

During the war with Veii in 393 BC, the level of Lake Albano rose to an unusual height even in the absence of rain. This prodigy was believed to be relevant on the siege of Veii because a haruspex from Veii recited some lines of a prophecy that illustrated the relationship between the level of its waters and either the safety or the fall of the town to the Romans. It foretold that as long as the waters of the lake remain high Veii would be impregnable to the Romans. If the waters of the lake were scattered in an inland direction on the other hand Veii would fall, but if they were to overflow through the usual streams or channels toward the sea this fact would be unfavourable to the Romans as well.

Dumézil ascribed this story to the Roman custom of projecting religious legendary heritage onto history, considering it as a festival myth, aimed at giving relevance to an exceptional event which would have happened during the Neptunalia. This legend would show the scope of the powers hidden in waters and the religious importance of their control by man: Veientans too knowing the fact had been digging channels for a long time as recent archaeological finds confirm. There is a temporal coincidence between the conjuration of the prodigy and the works of derivation recommended by Palladius and Columella at the time of the canicula, when the waters are at their lowest.