I think the discovery of 'Hydraulic' cement using pulverised volcanic ash from Pozzuoli made a huge step forward in architecture.
Concrete that sets under water made it possible to build viaducts and aquaducts across river beds etc. The construction of artificial harbour walls made it possible to dramatically increase trading between nations.
In Rome the building of the dome of the Pantheon is a masterpiece in the use of early concrete and still stands more than 2000 years after it's construction.
Julian Calendar and the roman numerals
Cement, glass, and sail boats are three inventions that originated in Rome and are still used today.
My BATTY
The romans invented the arrows,and the spear and more...................................................
The dome, arch, paved roads, the arena, government, laws, cement, are all out of ancient Rome.
the dome. Rome's key contribution was its support and encouragement of Christianity.
i dont realy know
A thing, invention, and I don't Know and so on and on and on......
The major river of Rome is the Tiber River.
There are no major cities in Rome - Rome is a city, the capital city if Italy. (It you meant to ask - "What are the major cities of the ancient Roman Empire" - then ask this as a separate question).
Rome gave us may contributions in many areas but perhaps the greatest contribution they handed down to us is the concept of civil rights. Their ideas on personal freedoms and rights are still practiced, with modifications for the times, by all the western countries on the planet.
Rome, Italy is a city.