The ancient Romans were famous for their advanced engineering accomplishments. Technology for bringing running water into cities was developed in the east, but transformed by the Romans into a technology inconceivable in Greece. The architecture used in Rome was strongly influenced by Greek and Etruscan sources.
Roads
Roads were common at that time, but the Romans improved their design and perfected the construction to the extent that many of their roads are still in use today. Their accomplishments surpassed most other civilizations of their time, and after their time, and many of their structures have withstood the test of time to inspire others, especially during the Renaissance. Moreover, their contributions were described in some detail by authors such as Pliny the Elder, so there is a printed record of their many inventions and achievements.
Aqueducts
A thousand cubic metres (260,000 US gal) of water were brought into Rome by eleven different aqueducts each day. Per capita water usage in ancient Rome matched that of modern-day cities like New York City or modern Rome. Most water was for public use, such as baths and sewers. De aquaeductu is the definitive two volume treatise on 1st century aqueducts of Rome, written by Frontinus.
The aqueducts could stretch from long, and typically descended from an elevation of above sea level at the source, to when they reached the reservoirs around the city. Roman engineers used inverted siphons to move water across a valley if they judged it impractical to build a raised aqueduct. The Roman legions were largely responsible for building the aqueducts. Maintenance was often done by slaves.
The Romans were among the first civilizations to harness the power of water. They built some of the first watermills outside of Greece for grinding flour and spread the technology for constructing watermills throughout the Mediterranean region. A famous example occurs at Barbegal in southern France, where no fewer than 16 overshot mills built into the side of a hill were worked by a single aqueduct, the outlet from one feeding the mill below in a cascade.
They were also skilled in mining, building aqueducts needed to supply equipment used in extracting metal ores, e.g. hydraulic mining, and the building of reservoirs to hold the water needed at the minehead. It is known that they were also capable of building and operating mining equipment such as crushing mills and dewatering machines. Large diameter vertical wheels of Roman vintage, for raising water, have been excavated from the Rio Tinto mines in Southwestern Spain. They were closely involved in exploiting gold resources such as those at Dolaucothi in south west Wales and in north-west Spain, a country where gold mining developed on a very large scale in the early part of the first century AD, such as at Las Medulas.
Bridges
Roman bridges were among the first large and lasting bridges ever built. They were built with stone, employing the arch as basic structure. Most utilized concrete as well. Built in 142 BC, the Pons Aemilius, later named Ponte Rotto (broken bridge) is the oldest Roman stone bridge in Rome, Italy.
The biggest 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 both in terms of overall and span length. They were normally at least 18 meters above the body of water.
An example of temporary military bridge construction is the two Caesar's Rhine bridges.
Dams
The Romans built many dams for water collection, such as the Subiaco dams, two of which fed Anio Novus, the largest aqueduct supplying Rome. One of the Subiaco dams was reputedly the highest ever found or inferred. They built 72 dams in Spain, such as those at Mérida, and many more are known across the empire. At one site, Montefurado in Galicia, they appear to have built a dam across the river Sil to expose alluvial gold deposits in the bed of the river. The site is near the spectacular Roman gold mine of Las Medulas.
Several earthen dams are known from Britain, including a well-preserved example from Roman Lanchester, Longovicium, where it may have been used in industrial-scale smithing or smelting, judging by the piles of slag found at this site in northern England. Tanks for holding water are also common along aqueduct systems, and numerous examples are known from just one site, the gold mines at Dolaucothi in west Wales. Masonry dams were common in North Africa for providing a reliable water supply from the wadis behind many settlements.