Valmiki Ramayana Yuddha Kanda Sarga 75 Shloka 40

कैलासशृङ्गप्रतिमम् the entrance gate of the city that was like Kailasa, तत्पुरगोपुरम् which resembled, तस्य its, कार्मुकमुक्सैश्च shaft released from bow, शरैः arrows, विशीर्णम् crumbled, भुवि on the ground, अपतत् fallen.

The entrance gate of Lanka, which was like Kailasa, crumbled and fell by the shaft released from the bow of Rama.