Anyone who has balanced a broom stick knows this is easy. The entire weight of the pole is focused down into the man's hand. Yet, if the same man tries to hold the pole horizontally, he will fail. Gravity is operating on the whole length of the pole. No one can hold that much weight with even two hands, let alone only one.
Gravity is the worst enemy of a building.
Just as the man could hold the pole vertically and not horizontally, a vertical wall or column stands against gravity better than a horizontal roof or raised floor. History's ruins have proved that walls and columns stand the longest. This double curve, the combination of vertical and horizontal components, makes a dome strong. A Monolithic Dome is a thin shell structure similar to ordinary chicken eggs. Try this experiment.