This is a good question. There are many technologies the Romans used to help them in governing such a vast empire. Let me name a few of the most important.
First, the Romans created roads. This might seem like a small thing, but in the ancient world, there were no roads. So, with the Roman roads, the Romans were able to travel so much faster, which was essential for communication, military operations, and trade.
Second, the Romans build bridges. This enabled the Romans to cross rivers when they needed to. This would help once again in communication and trade. Some of their bridges still exist today. For example, the city of Trier in Germany still uses a Roman bridge.
Third, the Romans also build aqueducts to bring water from far distances. For this reason, they were able to build cities that could be sustained. This was essential for all cities.
Rome may have created Roads, but Roads are not from Rome as everyone knows. All of Asia was greatly roaded in city areas around India.
Persia had roads, who invaded Greece [region of Rome before the empire]. All the armor including the art and much of the architecture is Persian | West Asian | Northern Indian. If you saw the movie 300, the part it leaves out in the movie in the end is, Sparta fell. There is no Sparta, and for that matter, no Rome today.
One thing in mind is "There are no Lions in Rome"..The Lion symbol which is also on many other flags today, shows the mixture of cultures coming through that region over the centuries.