Also known as, the "Western Wall," the Wailing Wall is the only outer wall of the Temple that remained after Rome destroyed the second Temple in 70 AD. This remnant of what was the most sacred structure for the Hebrews grew into a holy site for Jews. Because of the heartfelt prayers at the Western Wall, it became known as the "Wailing Wall" because Jews insert their paper-written requests inside the wall's cracks as they pray.
Psalm 122:6-7
Pray for peace in Jerusalem. May all who love this city prosper. O Jerusalem, may there be peace within your walls and prosperity in your palaces. (NLT)