The Roman Empire really adopted much of Greek culture, and this was even more true with the eastern portion of the Empire that was thoroughly Greek. When speaking of the culture, it is often referred to as Greco-Roman because of how much the culture really spread.

Part of this was simple assimilation. The Roman Empire took over what was the Greek Empire, and because of that, the Greek culture was present. This was even more exacerbated by the fact that the Greek Empire had been so dominate. Because of that, much of the culture had already been wide spread.

Because of that, Greek had already become the lingua Franca of the area. When Rome took over, they kept much that in place. While Latin was their official language, they continued with the Greek as a popular language as it already was dominant.

Rome also held older cultures and religions in high regard. It was one of the reasons why ideas, such as Judaism, were given special treatment. With the Greek culture, the Romans saw it almost as a golden age, something to replicate.

This can also be seen in just the religion. The Greek religion, or their mythology, was nearly fully adopted by the Romans. The names were changed, and some extra ideas were created, but the base was kept.

Comparing the art as well, we see many similarities. The styles in Rome were largely adopted from the Greeks. One place we can see this is in how they depicted wise individuals. As according to Greek tradition, wise figures in Roman lore were also depicted with full beards and long hair. This was eventually replaced when the Roman Emperors started sporting a more clean shaven look. But looking at the Byzantine Empire (Eastern Romans), the long hair, full beard look continued (we can especially see this in how Jesus was depicted).

So the Greek culture was very dominant. It was changed and adapted to Rome, but it’s influence is unmistakable.