The Temple Mount, also known as Mt. Moriah and al-Haram al-Sharif ("the noble sanctuary"), has been considered the holiest spot in Jerusalem for the entire period of the city's human habitation. It is presently a raised, flat area, roughly rectangular, on the south-eastern edge of the old walled city of Jerusalem. The Golden Gate (or Gate of Mercy) opens into the Temple Mount on its eastern wall, and the Sealed Gates would open on the southern wall, if they weren't sealed. The southern part of the western edge of the Temple Mount is an abrupt, walled drop into the city, the Western, or Wailing, Wall. Just to the east, the Mount of Olives looks down on it from outside the city. To the west is the old Jewish Quarter of Jerusalem, and the north, the old Muslim Quarter. The Dome of the Rock is roughly in the middle of the Temple Mount, probably on the site of the Jewish Temple(s), and the Al-Aqsa Mosque is on the southern end.
In the pre-Jewish period, Jerusalem was occupied by a Semitic-speaking people called the Jebusites (who were an actual ethnic group, and not an anachronistic Simpsons reference) who perhaps called it Ur-Shalem, or city of Shalem. The Temple Mount would have lain just north of the city proper in those days, which was built up on Ophel Hill, also known as Mt. Zion, just south of the present extent of the city walls. The Temple Mount was a bit higher and rockier at that point, with a smaller flat expanse at its peak. Archaelogists speculate that the Temple Mount was the sacred spot of Shalem, who was the Jebusite patron deity of the city and its namesake.
The Bible, and some Muslim traditions, records the Temple Mount as the place where Abraham was ordered by God to sacrifice Isaac, (or possibly Ishmael, to Muslims), though currently, most Muslims place it has having happened in what is now Saudi Arabia, near Mecca. There is also a strong Jewish and Muslim tradition identifying the rock on the peak as the spot where God stood during the Creation, and the place where Adam came to dwell after his expulsion from the Garden of Eden. The Bible says that King David purchased the Temple Mount, to erect an altar to God, from Araunah the Jebusite, who had it as his threshing-floor, for fifty shekels. Araunah, presumably the Jebusite king of the area, wanted to donate it, but David insisted on paying. Some Jewish extremists use this transaction, which happened around 3000 years ago, as the proof that the Temple Mount remains sole property of Israel.
The First Temple on the Temple Mount was built by Solomon, David's son, around the 11 century BCE. It was a masonry and cedar construction, probably in the style of, though smaller than, the ziggurats built by the Jew's Semitic cousins in the fertile crescent, and would probably have been the most impressive and noticeable building in the city. Only certain people would have been allowed on the Temple Mount during this period, only priests within the Temple itself, and only the High Priest allowed, once a year, into the Holy of Holies where God was believed to have dwelled, symbolically or literally.
The First Temple was destroyed, along with the rest of Jerusalem, by the Babylonians in 587 BCE. In 537 BCE, after the end of the Babylonian Captivity, the Second Temple was built, in roughly the same style as the first, under Persian patronage. After the revolt of the Maccabees in 167 BCE(against the Seleucids, who had defiled the Temple with an idol to Antiochus Epiphanes), the Temple was rededicated, and a small fort, the Baris, built at the north-west corner of the Temple Mount.
In the late 1st century BCE, Herod, the Roman king of Judaea and a convert to Judaism, enlarged and rebuilt the Second Temple in a more Roman architectural style, as well as undertaking a massive campaign of terrain leveling which gave the Temple Mount its current flat-topped rectangular shape, and enlarging the Baris into the Antonia Fortress, where the trial of Jesus is supposed to have taken place.
In 70 CE, following an unsuccessful Jewish rebellion against Rome, the temple was destroyed for good by the Emperor Titus, and the Jews expelled from the city. The Jews briefly regained possession of the city during Bar Kochba Rebellion, from 132-135 CE, but this was also mercilessly crushed, by Hadrian, who afterwards built a temple to Jupiter on the site of the old Second Temple and renamed the city Aelia Capitolina to dispel any lingering aura of Jewishness about it.
The Byzantine Christians, whose occupation of the city can be considered as having started in 326 CE, on the visit of Constantine's mother, Helena, to Jerusalem, re-renamed, or perhaps un-renamed, the city back to Jerusalem, and destroyed the Temple to Jupiter. The Jews were allowed to return to the city once a year under the Byzantines, on the 9th of the Jewish month of Av, where a small delegation was allowed to approach the Western Wall and lament the destruction of the Temple. The Byzantine period was the only point in Jerusalem's history where the Temple Mount was not an important and dominating part of the city's geography; the Byzantines, who were also quite keen on the idea of obliterating any memory of the city's Jewish identity, turned it into a garbage dump.
The Muslim caliph Umar conquered the city, bloodlessly, in 638 CE, and allowed the Jews to return to the city in full force, and ordered the three centuries of trash which had accumulated on the Temple Mount cleared, as well as building a wooden structure that would become the al-Aqsa Mosque. The Dome of the Rock was constructed in 691 CE by Abd al-Malik, for a set of complex reasons that I explore in its node, and the al-Aqsa Mosque rebuilt in stone a bit later. The Dome and the al-Aqsa Mosque are the only significant historic structures that survive on the Temple Mount today, aside from bits of the Antonia Fortress. The Arabic name for Jerusalem was al-Quds, or The Holy, though they, unlike the Romans, didn't try to suppress the older name.
The first period of Muslim rule in Jerusalem remains the high water mark for religious tolerance in the city, with all three monotheistic faiths living in the city in relative harmony, aside from a brief interlude under the more-or-less mad Fatimid sultan al-Hakkam, who expelled Jews and Christians from the city, though this edict was rescinded immediately on his death. Around the 10th century, the Temple Mount became identified in Muslim thought with the site of "the far mosque", the place of the start of The Prophet's Night Journey, the spot where the Prophet had met the biblical patriarchs and then embarked on a visit, either physically or spiritually, during a dream, to Paradise to speak with Moses and God.
When the Crusaders took Jerusalem in 1099, they immediately expelled the Muslims from the city, and re-re-re-re-re-expelled the Jews. They did not, as one might expect, destroy the Dome of the Rock and al-Aqsa Mosque and replace them with churches, but this was because of, frankly, more abject stupidity than any kind of spirit of tolerance. The Crusaders, in a touchingly thick bit of naiveté and idealism, believed that the Dome of the Rock was actually the First Temple, and the al-Aqsa Mosque was Solomon's palace (which wouldn't have even been located anywhere near that site). The Temple Mount became one the centers of Crusader government; the al-Aqsa Mosque became the headquarters of the powerful Knights Templar, and the Dome of the Rock their symbol.
When Saladin retook the city in 1187, he simply rededicated the Dome and the Mosque, presumably a bit agape at his good luck, and readmitted the Jews to the City. Jerusalem proceeded for almost a millennium under a series of relatively tolerant Muslim dynasties, acquiring a significant Jewish minority who lived around the Temple Mount and the Western Wall. During the British Mandate, the Temple Mount remained under Arab control, as it did after the foundation of modern Israel, when it was under the aegis of the government of Jordan. It was captured by the Israelis in 1967 during the Six Day War, but Moshe Dayan allowed local Palestinian Arabs to retain day-to-day control of it.
Today the Temple Mount remains one of the most significant symbols of the contention over Jerusalem. For Muslims it is a rallying point, the site of the Night Journey and two of the most beautiful and holy buildings of Islam, a symbol of the long Muslim connection with al-Quds. For Jews, it is the site of the lost temple, both the holiest spot in Judaism and a symbol of the many trials and tribulations the Jews have been through, as well as the promise of the Messianic Age when the Temple will once more be rebuilt. Indeed there are some Jewish extremist groups who want to usher in the Messianic Age themselves by rebuilding the Temple, an idea that, as one might imagine, causes Muslims no small consternation. The future of the Temple Mount is uncertain, hidden in an ever-shifting mélange as symbols as rich and complicated as its history.