How the Kotel Remained
When the Roman Legions laid siege to the Temple Mount in Yerushalayim they divided their forces into four divisions. The officer in charge of each was instructed to destroy one of the four walls which surrounded the sacred mountain.
Three of them indeed carried out this order but one left the wall entrusted to him intact. When the emperor reprimanded him for failing to follow his orders, the officer explained:
Had I destroyed that wall as did the other officers, future rulers would not be able to appreciate what grandeur you succeeded in destroying. Now that I left this wall untouched, future generations will be able to marvel at the destruction you achieved!
Tradition has it that the wall he left alone was the Western Wall the Kotel.