The mountains and hills created a barrier so attackers would have a hard time invading. Mountains also provided a source of water for the Romans.
Rivers were also a barrier to attackers because they would have a hard time crossing the rivers. Rivers, like mountains, created a steady source of fresh water. Lakes were also an easy way to transport things from place to place.
The Mediterranean Sea, just like the mountains and the rivers, created a natural barrier from attackers. This sea also gave a source of food and was a highway for trading and shipping.
Roads were made to be strong and durable and were used for trading, transporting, and for military purposes. Thousands of miles of roads ran throughout Rome.
Aqueducts were efficient at bringing water from the mountains and they were well built because many of them are standing today. Aqueducts were essential to the Romans.
The climate in Rome was Mediterranean Climate and was warm during the summers and this supported agriculture year round, just like California.