Number of visitors: 3 million
Location: Athens
One of the most ancient sites on the list, the Acropolis of Athens overlooks modern-day Athens (“Acropolis” means “high city” in Greek). Dating back to the 5th century BC, temples to the Greek gods once outfitted its hill, with the ruins available to tour today.
The crown jewel of Athens is The Parthenon, a spectacular temple built between 447 and 438 BC that served as a church and, later, a mosque under Turkish rule.
However, the Greek government has announced plans to cap visitor numbers to 20,000 per day in order to preserve the site.
Tickets: Start at €10 during the winter, €15 during the summer
