Engineering and construction.  
Wood.  
The Romans created fireproof wood by coating the wood with alum.  
Stone.  
It was ideal to mine stones from quarries that were situated as close to the site of construction as possible, to reduce the cost of transportation. Stone blocks were formed in quarries by punching holes in lines at the desired lengths and widths. Then, wooden wedges were hammered into the holes. The holes were then filled with water so that the wedges would swell with enough force to cut the stone block out of the Earth. Blocks with the dimensions of 69 by 14 by 15 ft (21.0 by 4.3 by 4.6 m) have been found, weighing about 1000 tons. There is evidence that saws were developed to cut stone in the Imperial age. Initially, Romans used saws powered by hand to cut stone but later went on to develop stone cutting saws powered by water.  
Cements.  
The mixture ratio of Roman lime mortars depended upon where the sand for the mixture was acquired. For sand gathered at a river or sea, the mixture ratio was two parts sand, one part lime, and one part powdered shells. For sand gathered further inland, the mixture was three parts sand and one part lime. The lime for mortars was prepared in limekilns, which were underground pits designed to block out the wind.  
Another type of Roman mortar is known as pozzolana mortar. Pozzolana is a volcanic clay substance located in and around Naples. The mixture ratio for the cement was two parts pozzolana and one part lime mortar. Due to its composition, pozzolana cement was able to form in water and has been found to be as hard as natural forming rock.  
Cranes.  
Cranes were used for construction work and possibly to load and unload ships at their ports, although for the latter use there is according to the "present state of knowledge" still no evidence. Most cranes were capable of lifting about 6–7 tons of cargo, and according to a relief shown on Trajan's Column were worked by treadwheel.  
Buildings.    
The Pantheon.    
The Romans designed the Pantheon thinking about the concepts of beauty, symmetry, and perfection. The Romans incorporated these mathematical concepts into their public works projects. For instance, the concept of perfect numbers was used in the design of the Pantheon by embedding 28 coffers into the dome. A perfect number is a number where its factors add up to itself. So, the number 28 is considered to be a perfect number, because its factors of 1, 2, 4, 7, and 14 add together to equal 28. Perfect numbers are extremely rare, with there being only one number for each quantity of digits (one for single digits, double digits, triple digits, quadruple digits, etc.). Embodying mathematical concepts of beauty, symmetry, and perfection, into the structure conveys the technical sophistication of Roman engineers.  
Roman concrete was essential to the design of the Pantheon. The mortar used in the construction of the dome is made up of a mixture of lime and the volcanic powder known as pozzolana. The concrete is suited for use in constructing thick walls as it does not require to be completely dry to cure.  
The construction of the Pantheon was a massive undertaking, requiring large quantities of resources and man-hours. Delaine estimates the amount of total manpower needed in the construction of the Pantheon to be about 400 000 man-days.    
Hagia Sophia.  
Although the Hagia Sophia was constructed after the fall of the Western empire, its construction incorporated the building materials and techniques of ancient Rome. The building was constructed using pozzolana mortar. Evidence for the use of the substance comes from the sagging of the structure's arches during construction, as a distinguishing feature of pozzolana mortar is the large amount of time it needs to cure. The engineers had to remove decorative walls to let the mortar cure.  
The pozzolana mortar used in the construction of the Hagia Sophia does not contain volcanic ash but instead crushed brick dust. The composition of the materials used in pozzolana mortar leads to increased tensile strength. A mortar composed of mostly lime has a tensile strength of roughly 200 kilopascals (30 psi) whereas pozzolana mortar using crushed brick dust has a tensile strength of 3,000 kilopascals (500 psi). The advantage of using pozzolana mortar in the construction of the Hagia Sophia is the increase in strength of the joints. The mortar joints used in the structure are wider than one would expect in a typical brick and mortar structure. The fact of the wide mortar joints suggests the designers of the Hagia Sophia knew about the high tensile strength of the mortar and incorporated it accordingly.  
Waterworks.  
Aqueducts.  
The Romans constructed numerous aqueducts to supply water. The city of Rome itself was supplied by eleven aqueducts made of limestone that provided the city with over one million cubic metres of water each day, sufficient for 3.5 million people even in modern times, and with a combined length of 350 kilometres (220 mi).  
Water inside the aqueducts depended entirely on gravity. The raised stone channels in which the water traveled were slightly slanted. The water was carried directly from mountain springs. After it had gone through the aqueduct, the water was collected in tanks and fed through pipes to fountains, toilets, etc.   
The main aqueducts in Ancient Rome were the Aqua Claudia and the Aqua Marcia. Most aqueducts were constructed below the surface with only small portions above ground supported by arches. The longest Roman aqueduct, 178 kilometres (111 mi) in length, was traditionally assumed to be that which supplied the city of Carthage. The complex system built to supply Constantinople had its most distant supply drawn from over 120 km away along a sinuous route of more than 336 km.  
Roman aqueducts were built to remarkably fine tolerances, and to a technological standard that was not to be equaled until modern times. Powered entirely by gravity, they transported very large amounts of water very efficiently. Sometimes, where depressions deeper than 50 metres had to be crossed, inverted siphons were used to force water uphill. An aqueduct also supplied water for the overshot wheels at Barbegal in Roman Gaul, a complex of water mills hailed as "the greatest known concentration of mechanical power in the ancient world".  
Roman aqueducts conjure images of water travelling long distances across arched bridges, however; only 5 percent of the water being transported along the aqueduct systems traveled by way of bridges. Roman engineers worked to make the routes of aqueducts as practical as possible. In practice, this meant designing aqueducts that flowed at ground level or below surface level, as these were more cost effective than building bridges, construction and maintenance for bridges was higher than that of surface and sub-surface elevations. Aqueduct bridges were often in need of repairs and spent years at a time in disuse. Water theft from the aqueducts was a frequent problem which led to difficulties in estimating the amount of water flowing through the channels. To prevent the channels of the aqueducts from eroding, a plaster known as opus signinum was used. The plaster incorporated crushed terracotta in the typical Roman mortar mixture of pozzolana rock and lime.  
Dams.  
The Romans built dams for water collection, such as the Subiaco Dams, two of which fed Anio Novus, one of the largest aqueducts of Rome. They built 72 dams in just one country, Spain and many more are known across the Empire, some of which are still in use. 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.  
The Romans built dams to store water for irrigation. They understood that spillways were necessary to prevent the erosion of earth-packed banks. In Egypt, the Romans adopted the water technology known as wadi irrigation from the Nabataeans. Wadis were a technique developed to capture large amounts of water produced during the seasonal floods and store it for the growing season. The Romans successfully developed the technique further for a larger scale.  


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