Roman Empire
Architecture and engineering

The chief Roman contributions to architecture were the arch, vault and dome. Some Roman structures still stand today, due in part to sophisticated methods of making cements and concrete. Roman temples developed Etruscan and Greek forms, with some distinctive elements. Roman roads are considered the most advanced built until the early 19th century.

Roman bridges were among the first large and lasting bridges, built from stone (and in most cases concrete) with the arch as the basic structure. The largest Roman bridge was Trajan's bridge over the lower Danube, constructed by Apollodorus of Damascus, which remained for over a millennium the longest bridge to have been built. The Romans built many dams and reservoirs for water collection, such as the Subiaco Dams, two of which fed the Anio Novus, one of the largest aqueducts of Rome.

The Romans constructed numerous aqueducts. De aquaeductu, a treatise by Frontinus, who served as water commissioner, reflects the administrative importance placed on the water supply. Masonry channels carried water along a precise gradient, using gravity alone. It was then collected in tanks and fed through pipes to public fountains, baths, toilets, or industrial sites. The main aqueducts in Rome were the Aqua Claudia and the Aqua Marcia. The complex system built to supply Constantinople had its most distant supply drawn from over 120 km away along a route of more than 336 km. Roman aqueducts were built to remarkably fine tolerance, and to a technological standard not equalled until modern times. The Romans also used aqueducts in their extensive mining operations across the empire.

Insulated glazing (or "double glazing") was used in the construction of public baths. Elite housing in cooler climates might have hypocausts, a form of central heating. The Romans were the first culture to assemble all essential components of the much later steam engine: the crank and connecting rod system, Hero 's aeolipile (generating steam power), the cylinder and piston (in metal force pumps), non-return valves (in water pumps), and gearing (in water mills and clocks).
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