Manasara 9.162

9.162

catuḥpañca ca ṣaṭ sapta cāṣṭakaṃ vā'tha vīthikā
madhye vīthiṃ vinā kuryāccaturdigdvārakalpanam

there may be four, five, six, seven, or eight streets; / without a street in the middle, one should fashion gates in the four directions.