A dome is a type of roof or ceiling that is shaped like half of a sphere. Persian domes were invented thousands of years ago by the ancient Persians. They created them by making brick walls that curved inwards and overlapped in the middle - almost like the shape of an upside-down bowl. Then they added layers of mud and straw, topped with a layer of stone and finished with a layer of plaster. Finally, they decorated the surface with colorful tiles and intricate designs. These domes are some of the oldest and most iconic architectural features in the world. They were used to cover things like palaces, mosques, tombs, and other important places and have been admired by civilizations around the world ever since.