The Roman Empire spanned from 753 BCE to 337 CE, beginning as a monarchy and developing into a republic and then empire. Key events included the founding of Rome by Romulus and Remus in 753 BCE, the establishment of the Roman Republic in 509 BCE, Roman conquests of neighboring territories and Greece, and the rise of the Roman Empire under Augustus in 27 BCE. Art and architecture during this period was heavily influenced by Etruscan and Greek styles, including the widespread later use of concrete, and artistic styles evolved from realistic Republican portraits through various mural painting styles under the Empire. The Empire reached its greatest extent under emperors like Trajan, Hadrian, and the Antonines, before declining