Jews around the world are observing a predawn-to-dusk fast on Tuesday, the 17th of Tammuz on the Jewish calendar. The fast is scheduled to end at 8:07 p.m. in Jerusalem.
The primary focus is the breaching of the walls of Jerusalem by the Romans in the time of the Second Temple, three weeks before its destruction on the Ninth of Av. There are sources that say the Babylonians breached the wall en route to destroying the First Temple as well. The day also commemorates Moses' smashing the first tablets of the Ten Commandments following the sin of the golden calf, the end of daily sacrifices before the destruction of the First Temple, the erection of idols in the both Temples and Rome's burning of a Torah scroll in the Second Temple. Other tragedies were recorded outside of Israel.
Tuesday's fast opens a period of semi mourning for both Temples, which includes abstinence from a number of practices, including haircuts, listening to music, wearing new clothes and eating produce which one has not eaten in a while.