The Holy Temple in Jerusalem refers to two destroyed Jewish temples that once stood at the Temple Mount, a flat-topped man-made platform located in the Old City of Jerusalem. Currently, the site is occupied by two Islamic shrines, the Dome of the Rock, built in 691, making it the oldest Islamic structure in the world, and Al-Aqsa Mosque, built on the remains of a shrine constructed as early as 684.
Because of the holiness of this site in the Jewish religion, few Jews dare to walk on it. It is the third holiest site in Islam. As you might imagine, the site is a flashpoint of religious conflict. Some Jews expect the eventual construction of a Third Temple, either deeming it necessary for the coming of the Jewish Messiah, or asserting that the Temple will descend down from Heaven in conjunction with the Messiah's arrival.
The original Holy Temple was allegedly built by King Solomon in 957 BCE, to serve his kingdom. However, archaeological excavations of the surrounding territory have failed to find any evidence of an urban civilization in the area at that time, instead indicating the area was inhabited by no more than 5,000 nomadic pastoralists gathered in a few small villages at most. Still, the legend goes that King Solomon built the structure on the place where his father, King David, made repentance to God for either 1) performing the sin of counting the people of Israel, which he was instructed not to do, or 2) taking the wife of a king he had conquered. The First Holy Temple took the place of the Tabernacle of Moses (a mobile shrine) and the Tabernacles of Shiloh, Nov, and Givon.
In 587, the Babylonians invaded the city and burned the temple to the ground. All Jews were subsequently killed or recruited into captivity in Babylon. Over the ensuing decades, many Jews returned, and construction of a new Holy Temple commenced in 537 BCE. It was finished in 516 BCE, and served as the center of Jewish religion for almost six additional centuries. In 20 BCE, the non-Jewish Roman proxy "King of the Jews" (as declared by the Roman Senate) Herod the Great began extensive renovation work on the plateau, expanding it to its current size and completely renovating the Temple. The result, "Herod's Temple," is still called the Second Temple because sacrifices continued throughout the duration of the reconstruction.
In 70 BCE, the Romans were in the process of putting down continuous Jewish revolts, and decided to level the city of Jerusalem. All Jews in the city were either killed or enslaved, and the Second Temple was destroyed. The Arch of Triumph commemorating the sacking of the town, the Arch of Titus, still stands in Rome. Jews were devastated, however. Though all the walls of the Holy Temple still stand underground, only the Western Wall is exposed, and it remains one of the holiest sites in Judaism, if not the holiest.