Dome

A dome is a special curved roof that looks like the top half of a ball or sphere. It is an important part of many buildings and has been used for thousands of years. Domes can sit on round or square spaces, and they are made in many different ways using many kinds of materials.

People have built domes since very old times. You can find domes in buildings from ancient Mesopotamia, Persian, Hellenistic, Roman, and Chinese cultures. They were also used a lot in Byzantine architecture and Sasanian architecture, and later in Renaissance architecture, Ottoman architecture, Baroque, and Neoclassical architecture.

Today, domes are used in all sorts of buildings, from churches and government buildings to sports arenas and even everyday structures. They are made from many materials, including stone, wood, brick, concrete, metal, glass, and plastic. Domes often have special meanings, such as representing the sky or serving as important symbols in different cultures.

Etymology

The word "dome" comes from an old Greek and Latin word domus, meaning "house." Long ago, people used it to describe important buildings like churches, no matter what shape they were. Later, around the 18th century, the word started to mean a rounded roof shape, especially for big, fancy buildings. In French, a similar word, dosme, also came to mean a rounded roof or vault, shaping how we use the word today.

Main article: cupola

Definitions

Domes are curved-roof buildings that people have used for thousands of years. Long ago, people made roofs with curved shapes using wood and stone. The most common dome shape, like half of a ball, started with designs from ancient Greece and Rome, but other shapes were used too, especially in early Islamic buildings.

Today, the word "dome" can mean different things. Sometimes it only means shapes that look like half of a ball, and other times it means any rounded roof shape. Engineers and architects use the word in different ways—one group looks at how the building stays standing, while the other looks at how it looks. With new building materials, domes can now be made in many new ways, so the meaning of "dome" has become broader.

Elements

The word "cupola" is another word for "dome". It is usually used for a small dome on top of a roof or turret. The top part of a dome is called the "crown". Domes can be supported by a round or oval wall called a "drum". If the drum reaches the ground, the building might be called a "rotunda".

When a dome's shape doesn't match the walls below it, special techniques are used to connect them. One way is to use diagonal lintels to create an octagonal base. Another method uses arches to support the dome's weight. These methods help spread the weight of the dome evenly.

Materials

The earliest domes in the Middle East were made from mud-brick. Later, people used baked brick and stone. Wooden domes were also built because wood is light and flexible. It helped create wide spaces and was often covered with copper or lead roofs. Stone domes cost more and were smaller. Brick became popular for big buildings until the Industrial Age.

New materials like iron, steel, and concrete in the 19th and 20th centuries let builders make thinner and lighter domes. These could cover much larger spaces. These advances also allowed for movable domes in modern sports stadiums. In 1983, experimental domes made from rammed earth were created at the University of Kassel as part of research into sustainable architecture.

Shapes and internal forces

A masonry dome creates forces that push downward and outward. These forces can be thought of in two directions: like lines of longitude on a globe, which only push in, and like lines of latitude, which push in at the top but stretch at the bottom. The strength of these forces depends on how heavy the dome's materials are.

Domes are built in layers, with each layer forming a complete ring that supports itself. This makes them stable as they are built. Because of this, domes can be thinner than similar arches. The best shape for a dome allows it to push in perfectly without stretching, which helps it stay strong.

Symbolism

Main article: Symbolism of domes

Domes have been important symbols for a long time. In the past, people built dome-shaped tombs to honor their ancestors. This linked domes to the idea of a lasting home. In places like India and Iberia, domes were part of tombs and were considered sacred.

Later, domes also came to represent the heavens. In buildings, a dome placed over a square base carried special meaning: the circle symbolized the sky and perfection, while the square stood for the earth. This idea was used by rulers and became a key feature in religious buildings, where domes symbolized the sky and something holy.

Acoustics

Domes can change how we hear sounds because of their curved shapes. They can reflect sound and sometimes create echoes. Some domes have special areas called "whispering galleries" where a person can whisper and be heard clearly from far away. This shape can help carry music, like in old churches, but it might make speaking harder to understand.

To improve sound, some domes have small hollow spaces inside them. These spaces can spread out sound waves so that echoes are reduced and the atmosphere feels special. This idea of using special shapes and spaces to control sound has been known for a very long time.

Types

Domes come in many shapes and styles, each with its own special features. One common type is the beehive dome. It is made of horizontal layers that lean toward the center as they rise, meeting at the top. A famous example is the Treasury of Atreus from the Bronze Age.

Another type is the geodesic dome. It is made of a framework of triangles forming a pattern based on shapes like icosahedrons or octahedrons. These domes are strong and can be built using simple parts. Bulbous and onion domes are known for their rounded, curved shapes. They are often seen in Islamic and Russian buildings. Oval domes have an egg-like shape and were used as early as 4000 B.C. Each type of dome serves different purposes and shows the creativity of the cultures that built them.

Main article: Cloister vault

Main article: Ellipsoidal dome

Main article: Geodesic dome

History

Cultures have built domed homes for thousands of years using materials they had. Early homes were made from mammoth tusks and bones, found in Ukraine. Indigenous peoples also made dome-like homes, such as wigwams by Native Americans and igloos by the Inuit from snow.

Over time, domes changed from simple homes to more complex buildings. Ancient places like Mesopotamia, China, and the Roman Empire made their own dome styles. The Romans built big domes in baths, palaces, and tombs. The Pantheon in Rome is a famous example. These early domes helped shape future building designs.