Early civilizations depended on agriculturally-based economies. The the earliest civilizations often developed on rivers; the Mesopotamians developed on the Tigris and Euphrates Rivers, the Egyptians on the Nile, and the Indus peoples on the Indus River. Rome was no exception. One benefit the Romans had over these other civilizations is that they were centrally located on the Mediterranean Sea and had sufficiently developed naval technology in order to take advantage of their location.
Rome is located on the Italian peninsula and has access to both the Mediterranean Sea and Tiber River. The Tiber River provides fresh water for crops, irrigation, and drinking water. Rivers also provided a natural boundary for cities and territories. The Mediterranean Sea allowed traders to come and go via ports, bringing in fresh goods and exporting Roman surpluses. Not only did this encourage Rome to grow, but it enabled Rome to expand its empire across the Mediterranean Sea.
The Italian peninsula itself is protected to the north by the Alps, a mountain range that helps provide relative isolation. When the Romans engaged in war with the Carthaginians in the 3rd and 2nd centuries BCE, the Carthaginians were able to cross the Alps with their army of war elephants, but many of the elephants died crossing the peaks. This weakened the Carthaginian army. Not only is Italy isolated due to its mountain range, but Rome itself is protected to the East by the Apennines. The area around Rome itself only has low hills and flat lands, allowing for lush agriculture nourished by the Tiber River.