Brindisi

The city of Brindisi sits on the Adriatic Sea, near the bottom of the heel of Italy's boot. It's the capital of the province of the same name, in the region of Puglia.
Brindisi has long been an important sea port, thanks to its natural harbor. Before the ancient Romans arrived in the 3rd century B.C.E., this was already a Greek settlement. The geographical position of the city meant it was always in demand, and fell under the rule of several different empires over the centuries. Many of the main sights, then, showcase the different rulers from each period.
There is a 13th-century castle, an 11th-century cathedral, and two ancient Roman columns, among other historic monuments. There are arguably better beaches in Puglia, but there are plenty of lovely beaches in and around Brindisi, too. Brindisi is also a popular jumping-off point for ferry trips to Greece.

Practical Info

Brindisi is about 70 miles from Bari, the capital of Puglia. There's an airport in Brindisi, if you want to fly there directly. Train service in the south of Italy isn't as robust as it is in the north, so if you want to do much exploring outside Brindisi you should consider renting a car.