Bureaucracy! That is the main problem of the empire and mostly the republic. The republic fell because the size of the empire was to big, the events were moving rapidly and there was no time for bureaucracy, voting, debating and so on. When Rome became an empire it didn't of course change immediately. Some parts of the republic stayed enact. One of them was administrative bureaucracy. Luckily for the empire, after the third century crises, Diocletian started the dominate where the senate lost almost all of its power thus providing the empire with a more effective style of government where one man or two men, later three or four gave direct orders without having to debate and vote. That gave the empire 200 years more to live, although because of its size and changeable political currents it was never to last as a permanent state.
Trajan, who crossed the Danube added Dacia (Romania) to the Roman Empire, and he expanded into the East, although the Eastern provinces were abandoned by his successor Hadrian. Earlier, the Emperor Claudius added Britain to the Roman Empire.
A strong military
a major challenge confronting the Roman Empire was determining how to govern people from many different regions.
At the height of the Roman Empire in 117 AD, it's total size was 5,000,000 km2 (1,930,511 sq mi).
The Roman Empire was pretty advanced in government, services to the citizens, protection of the empire, building, and schools. In contrast, the middle ages was chaos. There was a lack of government, services, and advancement of any sort. People could no longer read or write, science was considered bad, and there was no protection offered by the government. Without the structure of the Roman Empire Europe fell into the "dark ages" for a 1000 years.
Communications and transport.
In pre-mechanical transport era, communication and movement of armies was slow and difficult. So they split the Empire into four to give two emperors and two caesars more manageable quotas.
Communications were a big problem with the size of the Roman empire. It could take a couple or three weeks for a message to get from Rome to, say, Alexandria. While the Roman roads made communications good in Italy and the continent, many cities had to be reached by roads and ships. Traveling by ship was slow and time consuming. There was also the problem of tax revenue from the provinces. Because of some of the long distances, many times part of the revenue "disappeared" in transit. Manpower for the army to defend the empire was also a problem which had to be dealt with by incorporating provincials into the army.
Communications and transport.
In pre-mechanical transport era, communication and movement of armies was slow and difficult. So they split the Empire into four to give two emperors and two caesars more manageable quotas.
Communication was one big problem. Even though the Romans had good roads and a signal system, it still could take days or sometimes weeks for a message to get from a province to Rome. And more time for the reply to get back to the province. Another problem was the various conditions in different parts of the empire. A law, that worked in Rome, for example, might not be reasonable or even enforceable in a place like Thrace or Dacia.
Communication was one big problem. Even though the Romans had good roads and a signal system, it still could take days or sometimes weeks for a message to get from a province to Rome. And more time for the reply to get back to the province. Another problem was the various conditions in different parts of the empire. A law, that worked in Rome, for example, might not be reasonable or even enforceable in a place like Thrace or Dacia.
Communication was one big problem. Even though the Romans had good roads and a signal system, it still could take days or sometimes weeks for a message to get from a province to Rome. And more time for the reply to get back to the province. Another problem was the various conditions in different parts of the empire. A law, that worked in Rome, for example, might not be reasonable or even enforceable in a place like Thrace or Dacia.
Communication was one big problem. Even though the Romans had good roads and a signal system, it still could take days or sometimes weeks for a message to get from a province to Rome. And more time for the reply to get back to the province. Another problem was the various conditions in different parts of the empire. A law, that worked in Rome, for example, might not be reasonable or even enforceable in a place like Thrace or Dacia.
The roman empire extended for about 4500 miles from west to east.
In pre-mechanical times it was impractical for communications and armies to travel effectively across Europe.
Communication was one big problem. Even though the Romans had good roads and a signal system, it still could take days or sometimes weeks for a message to get from a province to Rome. And more time for the reply to get back to the province. Another problem was the various conditions in different parts of the empire. A law, that worked in Rome, for example, might not be reasonable or even enforceable in a place like Thrace or Dacia.