Matsya Purana — Navagraha Sacrifice for Planetary Pacification and Prosperity
प्रागुदक्प्लवनां भूमिं कारयेद्यत्नतो बुधः प्रागुत्तरं समासाद्य प्रदेशं मण्डपस्य तु //
prāgudakplavanāṃ bhūmiṃ kārayedyatnato budhaḥ prāguttaraṃ samāsādya pradeśaṃ maṇḍapasya tu //
A wise man should, with due care, have the ground prepared so that it slopes (for drainage) toward the east and north; and he should choose, in particular, the eastern or northern portion as the site for the maṇḍapa (pavilion).
This verse does not discuss Pralaya; it focuses on Vastuvidya—practical rules for preparing land and selecting the mandapa’s placement with auspicious orientation and proper drainage.
It frames construction as a dharmic duty requiring careful planning: a king or householder should ensure correct site selection and orientation to support orderly ritual life, public welfare, and auspiciousness in built spaces.
It prescribes a site that slopes toward east/north (good drainage and auspicious flow) and recommends placing the mandapa toward the east or north sector—key Vastu Shastra principles for pavilion/temple adjunct layout.