Rome was the most successful civilization prior to 300 CE because it made many advancements and achievements, for example creating a republic, aqueducts, and the Colesseum, that had never even been thought possible before.
Rome was a very advanced civilization. Many of the bases of their successes came from Greece, but they took everything Greece had developed and made it bigger and better. The Romans came up with the idea to create a republic. This was the first time in Roman history that people from all social classes had some sort of say in the government. The Romans also created cement. Cement was a very big breakthrough in architecture and building. It became Rome's main building material because it was so strong and durable. The aqueducts were probably Rome's greatest achievement. They provided Rome with a huge water supply daily. These aqueducts made the creation of public baths, fountains, and other public works possible. Another Roman creation that shows how advanced and powerful their civilization was, is the Colosseum. The Colosseum was built structurally very well, and had such great detail. All of these, plus so many of the other great accomplishments made by Rome show how dominant of a civilization it was.