Luke 19:41-44 "And as he came still nearer to the city, he caught sight of it and wept over it, saying, “Ah, if you only knew, even at this eleventh hour, on what your peace depends—but you cannot see it. The time is coming when your enemies will encircle you with ramparts, surrounding you and hemming you in on every side. And they will hurl you and all your children to the ground—yes, they will not leave you one stone standing upon another—all because you did not know when God Himself was visiting you!" J. B. Phillips
This day was so important that Jesus wept and foretold a judgement on Jerusalem because they didn't know this was a time of visitation. Their Prince arriving as prophecies by Daniel 9:25 “Know therefore and understand, that from the going forth of the command to restore and build Jerusalem until Messiah the Prince, there shall be seven weeks and sixty-two weeks; the street shall be built again, and the wall, even in troublesome times.”
This is why He wept, because if they would of calculated the time they would known that it was Messiah the Prince that was riding in on that donkey colt. For the day of the command to that day was exactly 483 or 173,880 days (prophetic years are 360 days) they should of known it was the time of God Himself visiting them.