When digging a pit, one way to prevent the walls from collapsing inward under pressure is to make them less steep, so they slant outward like the sides of a cone. A good rule of thumb is to make ...

After digging a pit for the courtyard, which can range between 6 meters to 10 meters (20 feet to 33 feet) deep, the rooms are then carved out from the four walls of the sunken courtyard.