Kautilya's Arthashastra 2.3.30

2.3.30

mukhasamaḥ saṃkramaḥ saṃhāryo bhūmimayo vā nirudake //

Of the first floor, five parts (are to be taken) for the formation of a hall (sálá), a well, and a boundary-house; two-tenths of it for the formation of two platforms opposite to each other (pratimanchau); an upper storey twice as high as its width; carvings of images; an upper-most storey, half or three-fourths as broad as the first floor; side walls built of bricks; on the left side, a staircase circumambulating from left to right; on the right, a secret staircase hidden in the wall; a top-support of ornamental arches (toranasirah) projecting as far as two hastas; two door-panels, (each) occupying three-fourths of the space; two and two cross-bars (parigha, to fasten the door); an iron-bolt (indrakila) as long as an aratni (24 angulas); a boundary gate (ánidváram) five hastas in width; four beams to shut the door against elephants; and turrets (hastinakha) (outside the rampart) raised up to the height of the face of a man, removable or irremovable, or made of earth in places devoid of water.