From sundown on Monday, July 15 to nightfall on Tuesday, July 16, 1957. 17 Tamuz 5717 · צום י״ז בתמוז The Seventeenth of Tammuz (Biblical Hebrew: שִׁבְעָה עָשָׂר בְּתַמּוּז, Modern: Shiv'á Asár beTammúz, Tiberian (SBL): Šib̲ʿāʿāśār bəṯammuz) is a Jewish fast day commemorating the breach of the walls of Jerusalem before the destruction of the Second Temple. It falls on the 17th day of the Hebrew month of Tammuz, the fourth month, and marks the beginning of The Three Weeks, a mourning period leading up to Tisha B'Av. The day also traditionally commemorates the destruction of the two tablets of the Ten Commandments and other historical calamities that befell the Jewish people on the same date. Wiki link Dates: Hebcal.com (CC BY 4.0), Diaspora schedule. Text: Wikipedia (CC BY-SA).