Valmiki Ramayana Yuddha Kanda Sarga 42 Shloka 18
Original Shlokaकाञ्चनानिप्रमृद्नन्तस्तोरणानिप्लवङ्गमाः । कैलासशिखराभानिगोपुराणिप्रमथ्यच ।।6.42.18।।
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काञ्चनानि golden, प्रमृद्नन्तस्तोरणानि breaking the gateways, कैलासशिखराभानि like the peaks of Kailasa mountain, गोपुराणि towers, प्रमथ्यच crushing, प्लवङ्गमाः monkeys went.
The Vanaras started breaking the golden gateways and crushing them which were like peaks of Kailasa mountain.