Today is the day they destroyed the Jewish temple in 70 A.D..
But that is not all. This is the same day that it was destroyed by Babylon too.
Notice how God remembers dates.
"Tisha B'Av (help·info) (Hebrew: תשעה באב or ט׳ באב, "the Ninth of Av,") is an annual fast day in Judaism, named for the ninth day (Tisha) of the month of Av in the Hebrew calendar. The fast commemorates the destruction of the First and Second Temples in Jerusalem, which occurred about 656 years apart, but on the same date. Accordingly, the day has been called the "saddest day in Jewish history".
Tisha B'Av falls in July or August in the Gregorian calendar. When the ninth of Av falls on Shabbat, the observance is deferred until Sunday the tenth (although that day is still referred to as Tish`ah be-Av). According to the Mishnah (Taanit 4:6), the day commemorates five events: the destruction of the Temples, the return of the twelve scouts sent by Moses to observe the land of Canaan, the razing of Jerusalem following the siege of Jerusalem in 70 CE, and the failure of Bar Kokhba's revolt against the Roman Empire.
The Tisha B'Av fast lasts about 25 hours, beginning at sunset on the eve of Tisha B'Av and ending at nightfall the next day. In addition to the prohibitions against eating or drinking, observant Jews also observe prohibitions against washing or bathing, applying creams or oils, wearing leather shoes, or having sexual relations. In addition, mourning customs similar to those applicable to the shiva period immediately following the death of a close relative are traditionally followed for at least part of the day, including sitting on low stools, refraining from work, and not greeting others.
- The twelve scouts sent by Moses to observe the land of Canaan returned from their mission. Two of the scouts, Joshua and Caleb, brought a positive report, but the others spoke disparagingly about the land which caused the Children of Israel to cry, panic and despair of ever entering the "Promised Land". For this, they were punished by God that their generation would not enter the land. Because of the Israelites' lack of faith, God decreed that for all generations this date would become one of crying and misfortune for their descendants, the Jewish people. (See Numbers Ch. 13–14)
- The First Temple built by King Solomon and the Kingdom of Judah was destroyed by the Babylonians led by Nebuchadnezzar in 586 BCE and the Judeans were sent into the Babylonian exile.
- The Second Temple was destroyed by the Romans in 70 CE, scattering the people of Judea and commencing the Jewish exile from the Holy Land.
- Bar Kokhba's revolt against Rome failed in 135 CE. Simon bar Kokhba was killed, and the city of Betar was destroyed.
- Following the Roman siege of Jerusalem, the razing of Jerusalem occurred the next year. A Temple was built in its stead to an idol.