Ancient Roman architecture adopted the external language of classical Greek architecture for the purposes of the ancient Romans, but differed from Greek buildings, becoming a new architectural style. The two styles are often considered one body of classical architecture. Roman architecture flourished in the Roman Republic and even more so under the Empire, when the great majority of surviving buildings were constructed. It used new materials, particularly concrete, and newer technologies such as the arch and the dome to make buildings that were typically strong and well-engineered. Large numbers remain in some form across the empire, sometimes complete and still in use.
Roman Architecture covers the period from the establishment of the Roman Republic in 509 BC to about the 4th century AD, after which it becomes reclassified as Late Antique or Byzantine architecture. Almost no substantial examples survive from before about 100 BC, and most of the major survivals are from the later empire, after about 100 AD. Roman architectural style continued to influence building in the former empire for many centuries, and the style used in Western Europe beginning about 1000 is called Romanesque architecture to reflect this dependence on basic Roman forms.
The Romans only began to achieve significant originality in architecture around the beginning of the Imperial period, after they had combined aspects of their original Etruscan architecture with others taken from Greece, including most elements of the style we now call classical architecture. They moved from trabeated construction mostly based on columns and lintels to one based on massive walls, punctuated by arches, and later domes, both of which greatly developed under the Romans. The classical orders now became largely decorative rather than structural, except in colonnades.
