According to Dr. Karen Carr at Portland State University, the ancient Romans did not invent concrete. Eastern Europeans used concrete around 5600 BC, which is the earliest known usage. Rather, the Romans borrowed the idea, and perfected concrete. Its use became widespread with the emperor Nero around 60 A.D. Concrete is a mixture of powdered limestone, various clays, sand, and gravel. When freshly made, it is like a thick paste. Once it hardens, it turns into a rock-like material. Romans used the perfected concrete to build fountains and terrace walls. Domes on top of Roman buildings, such as the The Pantheon of Hadrian, were made from concrete. In turn, other cultures borrowed the perfected Roman concrete freely, and concrete is used extensively throughout the world to modern times. Some items made from concrete include roads, building foundations and bridges.
In "The Influence of the Roman Arch," the authors point out that the Romans did not invent the arch. The arch was used by Egyptians, Babylonians, and Greeks for very small buildings. Rather, the Romans borrowed the idea and perfected it by building arches with concrete. Because of the perfected techniques, large arches could be built. An arch is half a circle in shape and are seen in the Colosseum and in the aqueducts. Large arches are very easy to build, requiring only a wooden framework to support the wet concrete until it dries. Other cultures borrowed the perfected arch form heavily. For example, the Arc de Triomphe built by Napoleon in Paris, France, uses the arch form as the central motif.
The Romans borrowed column designs extensively from various neighboring cultures, especially the designs for the tops. The top of a column is called a capital. Greek influences are seen in Corinthian capitals. This kind of capital uses ornate leaf designs based upon the leaf pattern of the acanthus plant. Another type of capital is called the scroll. This capital looks like an scroll, unfurled in the middle where the column is. Each side of the rolled up scroll overhangs the sides of the column. Today, column designs are freely borrowed and exchanged between all the architects of the world.
Obelisks are seen in many parts of Rome to this day. Emperors such as Augustus Caesar, Caligula and Constantine transported them to various parts of Rome. Because stone is an almost indestructible material, a 1912 map of Rome indicated about 13 obelisks standing in Rome. These are very well preserved, complete with the original Egyptian hieroglyphics carvings. To say the ancient Romans "borrowed" obelisks is an understatement. They literally took obelisks from Egypt, and transported them back to Rome to use as decorations.