Cement.
Depends on which buildings you're referring to.
too build alot of buildings.
Colloseum Arch of Titus theator of Marcellus emperors palace
The Romans used the arch to build large buildings and bridges.
The Romans built the piping for the water systems that was waterproof and leakproof; they also built the roofs of their buildings of waterproof tiles.
Cheaper to build and maintain.
Cheaper to build and maintain.
The Romans made extensive use of the arch to build large buildings, bridges, and water aqueducts.
the greek influence was only in philosophy and art
Usually concrete. Romans invented concrete.
We do not always build differently than the Romans. There are places on the planet that still build houses and small shops with four walls a tile roof and a floor. The identical way the Romans built their small structures. In our domestic buildings we differ from the Romans in our choices of materials and the safety of those materials concerning fireproofing, allergens and personal safety. In our public or industrial buildings we use steel beams, basements and subbasements and reinforced concrete. Power machinery is used in all of our construction work while the Romans used manpower.
no. The prime reason for any civilization to build was for housing. However many of the remains of the ancient buildings that we see today were for religious and in some way a political purpose. That's because those "public buildings" were constructed of more durable materials and of a larger size than the average home.