The Siege of Jerusalem in the year 70 was the decisive event of the First Jewish–Roman War. The Roman army, led by the future Emperor Titus, with Tiberius Julius Alexander as his second-in-command, besieged and conquered the city of Jerusalem, which had been occupied by its Jewish defenders in 66.
The siege ended with the sacking of the city and the destruction of its Second Temple. The destruction of both the first and second temples is still mourned annually as the Jewish fast Tisha B'Av. The Arch of Titus, celebrating the Roman sack of Jerusalem and the Temple, still stands in Rome.
Source : https://en.wikipedia.org/wiki/Siege_of_Jerusalem_(AD_70)