The compluvium was a hole in the roof over the atrium where the rain fell through, into the impluvium.

A roofed courtyard of a Pompeian house is called an atrium. It typically featured an open roof at the center, called a compluvium, which allowed rainwater to collect in a shallow pool called an impluvium. The atrium served as a central gathering space in the house, connecting other rooms and providing light and ventilation.

Oculus (plural oculi) in Latin means eye. The name referred to circular windows or openings.

On type of oculus was the stone opening of the impluvium of the houses of the rich and some public buildings. It lied 30 cm below the floor and was the top of an underground holding chamber which collected rainwater from the compluvium, the roofless central part of the atrium (courtyard) and had layers of gravel and sand to filter the water. These two words come from pluvia, the Latin for rain.

There is a circular opening at the top of the dome of the Pantheon in Rome. Originally this was a temple dedicated to all gods. Then it became a Christian church. The building is circular and its walls support the dome. The oculus is the only source of light. It creates a beam of light that reaches the floor and rotates during the day with the movement of the sun in the sky. It is not covered and the rainwater is cleared by drainage canals.

with dog and guinee pig poo

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In Ancient China, the people made their houses with mudbrick. These Houses had only one room, and had a roof made of thatch, which is from dry vegetation such as straw.

They made these houses by building up the layers of mud brick, and placing the thatch on top.