Luke's entry narrative names places that ancient travelers could picture immediately: Bethany, Bethphage, and the Mount of Olives. Together they locate Jesus on Jerusalem's eastern approach.
The terrain helps explain the sequence from obtaining the colt to descending toward the city and finally seeing Jerusalem.
The Mount of Olives is a ridge immediately east of Jerusalem across the Kidron Valley. Bethany lay on its eastern side, while Bethphage was associated with the approach nearer Jerusalem, though its precise ancient location is less certain. Travelers coming from the east crossed or rounded the ridge and then descended toward the city.
From western portions of the Mount of Olives, Jerusalem and the Temple area come dramatically into view. That geography gives natural force to Luke's statement that Jesus sees the city and weeps over it.
The place names are not decorative details. They let the reader follow a real approach in which the city emerges before Jesus as the crowd celebrates.
That makes Luke's juxtaposition especially powerful: public acclamation accompanies the descent, but when Jerusalem comes into view Jesus responds not with triumphal satisfaction but with lament over the judgment he foresees.