The Temple of Jersualem, also known as the Second Temple, was destroyed 70 AD during the climactic final battle of the First Jewish-Roman War.
Roman forces under future Emperor Titus surrounded Jerusalem and prepared for a siege. The Jewish defenders, who had successfully repealed other Roman attacks, also prepared for the battle, but poor leadership crippled the zealot’s forces before the battle had even began.
Titus made several attempts to take the city, successfully breaching the third and second walls of the city, but intense street to street fighting forced the Romans back to within the temple proper. Negotiations to end the violence failed, and the Romans resorted to a secret attack which accidentally set part of the city on fire, including the temple itself. The jewish holy day of Tisha B’Av commemorates this destruction.