Canto 3 -
Araṇya-kāṇḍa
Chapter 48: Sītā-devī Condemns Rāvaṇa
Text 3.48.11
प्राकारेण परिक्षिप्ता पाण्डुरेण विराजता।
हेमकक्ष्या पुरी रम्या वैडूर्यमयतोरणा॥
prākāreṇa parikṣiptā pāṇḍureṇa virājatā
hema-kakṣyā purī ramyā vaiḍūryamaya-toraṇā
prākāreṇa = wall; parikṣiptā = it is surrounded; pāṇḍureṇa = white; virājatā = by a bright; hema-kakṣyā = with golden palaces and yards 2; purī = the city; ramyā = is pleasant; vaiḍūryamaya-toraṇā = and gates of lapis lazuli.
It is surrounded by a bright white wall. The city is pleasant with golden palaces and yards as well as gates of lapis lazuli.
The wall surrounding Laṅkā was white because it was made of silver.