Halakhah sa Isaias 64:10: Mishneh Torah, Fasts & Shulchan Arukh, Orach Chayim

One who saw the cities of Judah in their destruction says, "Your holy cities have become a desert" (Isaiah 64:9), and tears. [If] he saw Jerusalem in its destruction, he says, "[Zion] has become a desert, etc." (Isaiah 64:9); the Temple in its destruction, says "Our holy Temple, our pride, etc." (Isaiah 64:10), and tears. And from where is one obligated to tear? From [Mount] Scopus. And when he reaches the [place of the] Temple, he tears another tear. But if he encountered the Temple first when he came from the way of the wilderness, he tears for the Temple and adds [to the tear] for Jerusalem.

2. One who sees Jerusalem in her destruction, says "Tzion is a desert, a desolation" (Isaiah 64:9) and rends (one's garments). And when one see the Beit HaMikdash says "Our holy Temple, our pride, Where our fathers praised You, Has been consumed by fire: And all that was dear to us is ruined." (Isaiah 64:10). And from where is one obligated to rend - from HaTzofim. And afterwards when he sees the the Mikdash, he rends another tearing. And all rendings are a tefach (handbreath). If one comes from the way of the desert that then he sees the Mikdash first. He rends on the Mikdash a tefach, and afterwards when he sees Jerusalem, he adds to the first rending a little bit.