Kautilya's Arthashastra 2.4.20

2.4.20

bahiḥ parikhāyā dhanuḥśatāpakṛṣṭāś caityapuṇyasthānavanasetubandhāḥ kāryāḥ, yathādiśaṃ ca digdevatāḥ //

Guardian deities of all quarters shall also be set up in quarters appropriate to them.

Likewise the principal gates such as Bráhma, Aindra, Yámya, and Sainápatya shall be constructed; and at a distance of 100 bows (dhanus = 108 angulas) from the ditch (on the counterscarp side), places of worship and pilgrimage, groves and buildings shall be constructed.