Ancient Roman Architecture

Ancient Romans used hydraulics and the influence of the Greeks and Phoenician while constructing their buildings. Their use of the arch and the use of concrete and bricks facilitated the building of the many aqueducts throughout the empire. They used mostly domes as their buildings because it gave a open public spacing such as baths and basilicas. For housing the Romans where very concerned with public hygiene. Their baths had under-floor heating which piped hot and cold water. Romans also built multi-story apartment called insulae. The cheapest and darkest rooms were at the bottom; the lightest and most desirable at the top. Windows were mostly small, facing the street, with iron security bars. Insulae's were often dangerous, unhealthy, and prone to fires because of overcrowding and haphazard cooking arrangements.

http://en.wikipedia.org/wiki/Ancient_Roman_architecture