Pula, a small town on Adriatic coast located on Istria peninsula is the best known for its many well preserved ancient Roman buildings, the most famous of which is its 1st-century amphitheatre, or Arena, one of the six largest surviving Roman arenas in the world. This is one of the best preserved amphitheatres from antiquity and is still in use today during summer film festivals.
The records and remains show’s that Pula has been inhabited for more than likely some three thousand years, but it really came alive in the latter days of the Roman republic, when Julius Caesar made it a Roman colony (45 B.C.). Two other notable and well-preserved ancient Roman structures are the 1st-century AD triumphal arch, the Arch of the Sergi and the temple of Rome and Augustus. (some parts taken from Wikipedia)