<P> The Roman Empire was one of the most technologically advanced civilizations of antiquity, with some of the more advanced concepts and inventions forgotten during the turbulent eras of Late Antiquity and the early Middle Ages . Gradually, some of the technological feats of the Romans were rediscovered and / or improved upon during the Middle Ages and the beginning of the Modern Era; with some in areas such as civil engineering, construction materials, transport technology, and certain inventions such as the mechanical reaper, not improved upon until the 19th century . The Romans achieved high levels of technology in large part because they borrowed technologies from the Greeks, Etruscans, Celts, and others . </P> <P> All technology uses energy to transform the material into a desirable object or uses some form of mechanics combined with another form to make something better . The cheaper energy is, the wider the class of technologies that are considered economic . This is why technological history can be seen as a succession of ages defined by energy type i.e. human, animal, water, peat, coal, and oil . The Romans used water power, and watermills were common throughout the Empire, especially to the end of the 1st century AD . They were used for cereals milling, sawing timber and crushing ore . They exploited wood and coal for heating . There were huge reserves of wood, peat and coal in the Roman Empire, but they were all in the wrong place . Wood could be floated down rivers to the major urban centres but otherwise it was a very poor fuel, being heavy for its caloric value . If this was improved by being processed into charcoal, it was bulky . Nor was wood ever available in any concentration . Diocletian's Price Edict can give us a glimpse of the economics of transporting wood . The maximum price of a wagon load of 1,200 lbs of wood was 150 d. (denari). The maximum freight charge per mile for the same wagon load was 20 d. per mile . Room heating was normally better done by charcoal braziers than hypocausts . But hypocausts did allow them to exploit any poor - quality smoky fuels like straw, vine prunings and small wood locally available . Hypocausts also allowed them to generate a humid heat for their baths . </P> <P> The Romans worked almost all the coalfields of England that outcropped on the surface, by the end of the 2nd century (Smith 1997; 323). But there is no evidence that this exploitation was on any scale . After c. 200 AD the commercial heart of the Empire was in Africa and the East where the climate severely limited timber growth . There was no large coalfield on the edge of the Mediterranean . </P> <P> Nevertheless, in Roman Egypt all the essential components of the much later steam engine were first assembled by the Greek Mathematician and Engineer Hero: </P>

The architecture and/or the road system of the romans