The Western Wall also known as the Wailing Wall, is located in the Old City of Jerusalem on the western side of Mount Moriah the Temple Mount. When King Herod refurbished the second Temple to a much grander scale the Western Wall was one of the many new structures built. Although it is only an outer wall of the Temple it is a very holy site for Jewish people.
When the Romans exiled the Jewish people in 70 CE, they destroyed the Second Temple, leaving only the Western Wall. As it is the only Temple structure still standing, it has become a place of prayer. Slips of paper containing messages to G-d are placed into cracks in the Western Wall. Many pray at the wall for the rebuilding of the Temple. Since Muslims control the Temple Mount, Jews are not permitted to go to it, so the Western Wall is the closest that Jewish people can get to the site of the Temple. Every day, three times a day some Jews pray at the wall that the Temple be rebuilt in their own lifetimes.
In 1948 when Israel was reborn Jews were denied entry to the Western wall and the Old City of Jerusalem as it was under Jordanian control. In 1967, during the Six-Day War, the Israelis attacked the Old City and reclaimed the Western Wall.