And the multitudes that went before, and that followed, cried, saying, Hosanna to the son of David: Blessed is he that cometh in the name of the Lord; Hosanna in the highest. And when he was come into Jerusalem, all the city was moved, saying, Who is this? And the multitude said, This is Jesus the prophet of Nazareth of Galilee. - Matthew 21:9-11 KJV
And some of the Pharisees from among the multitude said unto him, Master, rebuke thy disciples. And he answered and said unto them, I tell you that, if these should hold their peace, the stones would immediately cry out. Luke 19:39-40 KJV
The Pharisees therefore said among themselves, Perceive ye how ye prevail nothing? behold, the world is gone after him. - John 12:19 KJV
Christ's triumphal entrance into Jerusalem was not a secret matter. I find it interesting that the Pharisees didn't oppose this entrance. I mean, they definitely objected, but they didn't get their guards together and try and stop it. I think they didn't oppose Jesus and his royal welcome because they were taken off guard, and were likely surprised.
Calvin wrote about this occasion, "Under this despicable aspect of the flesh the majesty of the Spirit was apparent; for how would they have endured that Christ should be conducted into the city, attended by the splendor of royalty, with so great danger to themselves, if they had not been seized with astonishment?".
I pray that we all may be seized with astonishment and wonder at the majesty and glory of our Lord, and praise and exult him forever!