Rome became an empire in the first century BC when Julius Caesar and his successors expanded the territories under Roman control. The monuments, temples, and other landmarks of Rome are a vivid testimony to the power, ideas, and glory of the Roman Empire. Architecture, for example, was modeled in part on the Classical Greek style, but with its own distinct features, often grander and more ornate than Greek structures. Ancient Rome also took the ideas of the Greeks, particularly regarding law and government, and adapted them to the Roman context. This allowed the Romans to create their own unique political system, which was based on a combination of legal principles and military strength.