impluvium

This Roman house had a hole in its roof. On purpose.

Below it sits an impluvium: a shallow basin in the floor of the atrium that catches the rain.

The roof slopes inward, toward the opening called the compluvium, so the rain pours into the house.

The water sinks through gravel and sand into a cistern below, and is drawn up again through a stone well-head.

On hot days, the shallow pool cooled the air around it. Pompeii is full of them.

Its cousins: the impluvium houses of the Igbo in Nigeria, the courtyard howz of Persian houses, the patio fountains of Córdoba.

Impluvium. A pool that drinks the rain.