The holy day of the Tiber River was celebrated on May 15. It was a Roman festival when Vestals made sacrifices in honour of the Tiber River, thus ensuring a steady supply of water for the remainder of the cultivation period.
Sources
Jaczynowska Maria, Religie świata rzymskiego, Warszawa 1987
Zieliński Tadeusz, Religia Rzeczypospolitej Rzymskiej
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