Cities such as Rome, Capua and Neapolim - modern Naples - are just some examples. A brief note about Naples: Naples used to be called Parthenope, after a Greek siren, and was only later renamed by Augustus to Neapolim.
The Apennine Mountains. Regions such as Etruria, Latium, Tuscany, Campania, Apullia, and Sicily, taken from Carthage during the First Punic War. All of them full of many cultures with rich histories. The Sabines, the Romans, and lesser known groups such as the Sicilians - or Sicanians from the name of the brother of Sabinus, from which the "Sabines" are named, known as Sicanus.
There are several theories as to the name of the sea to Italy's west. A common one is that of Bacchus, the God of parties, who was abroad a ship and drowned everyone that had taken him from the island where he was sleeping except one man. The sailors that drowned, a crew called the "Tyrrheni", is thought to be the origin for the Tyrrhenian sea's name. The name might also be related to Tuscany, off the coast of which, in the North, the Tyrrhenian sea begins.
The sea to the East is known as the Adriatic, the northern part of the Ionian sea, the middle being the Epirotic and the southern part being the Achaian Sea. The Adriatic is sometimes known as the "Superus" sea, the sea above - contrasting with the "Inferus", a name sometimes attributes to the Tyrrhenian Sea.
In the North, Italy borders Cissalpine Gaul, which has often through history been a core province of the Roman Empire, with the city of Mediolanum serving as imperial capital, and many more famous cities such as Mantua, Genua, or Aquilonia.
Beyond the seas, to the East is Istria, or Histria, named after the Ister - which is an old name for the Danube river, that goes from Germany all the way to modern Romania, where it finishes it's journey in flowing into the Pontus [Sea] - The Black Sea - ending it's course through a final area which is known as the Danube Delta.
To the West, there are the two islands of Corsica and Sardinia, named after Sardus, a son of Hercules that left Libya - Africa - with a handful of men and sailed to Sardinia, settling it.
There is also the island of Sicily to the South, beyond which to the southwest are Carthaginis - also known as Zeugis - and Numidia, which encompassed modern day Northern Algeria.