Visitors going to Rome’s Pantheon, one of the ancient world’s best preserved monuments, will have to pay an entrance fee from Monday.
Italy’s tourism ministry has said it will cost 5 euros (£4.30) to enter the church from next week.
The vast cylindrical former temple has an undamaged exterior wall which supports a 142 ft dome.
Every year, the landmark attracts millions of visitors, making it one of Italy’s top tourist draws.
The long-delayed introduction of a charge is part of a drive to squeeze more profit from Italy’s cultural assets, with the tourism ministry set to receive 70% of the revenue to help cover cleaning and maintenance.
The rest will go to the Diocese of Rome.
Entrance will still be free of charge for worshippers during religious services.
The Pantheon’s current form and six-metre-thick walls date from the early part of the reign of Emperor Hadrian, who came to power in AD 117.
It remains the world’s largest unreinforced concrete dome and has a circular skylight at its crown.
The building survived the Barbarian attacks on Rome and was transformed into a Christian church in 609.
Queuing up for one of the last free tickets on offer, German tourist Karsten Kohler said on Friday: “If it’s going to stay for another 2,000 (years), they need some money.”
Caring for art and architecture has long posed a challenge for a country that is responsible for more UNESCO world heritage sites than any other and has long-standing problems of bureaucracy and low public funding.