On the mount of Olives, over against the temple - The Mount of Olives was directly east of Jerusalem, and from it there was a fine view of the temple.
Matthew Henry
Concise Bible Commentary
See how little Christ values outward pomp, where there is not real purity of heart. He looks with pity upon the ruin of precious souls, and weeps over them, but we do not find him look with pity upon the ruin of a fine house. Let us then be reminded how needful it is for us to have a more lasting abode in heaven, and to be prepared for it by the influences of the Holy Spirit, sought in the earnest use of all the means of grace.