Kautilya's Arthashastra 2.3.32

2.3.32

prākāramadhye vāpīṃ kṛtvā puṣkariṇīdvāram, catuḥśālam adhyardhāntaraṃ sāṇikaṃ kumārīpuram, muṇḍaharmyadvitalaṃ muṇḍakadvāram, bhūmidravyavaśena vā niveśayet //

In the centre of the parapets, there shall be constructed a deep lotus pool; a rectangular building of four compartments, one within the other; an abode of the Goddess Kumiri (Kumárípuram), having its external area one-and-a-half times as broad as that of its innermost room; a circular building with an arch way; and in accordance with available space and materials, there shall also be constructed canals (kulyá) to hold weapons and three times as long as broad.