Venice will extend its experiment on charging tourists on day trips to the Italian city an admission fee into 2025.

The city listed as a UNESCO World Cultural Heritage site began conducting the trial this year amid concerns over negative impacts on the environment exerted by visits by excessive numbers of tourists.

To address the issue of "overtourism," the city charged its day-trippers 5 euros, or roughly five-and-a-half dollars, for a total of 29 days on a trial basis. The test focused on a period from April through July when the numbers of tourists increase substantially.

Next year, the city will charge the same amount for a total of 54 days over the same period. But those who do not book online four days prior to their visits will have to pay double the amount.

They will also face a fine for not carrying a reservation certificate issued at the time of the booking.

Reuters news agency reported that about 485,000 people paid for a day pass this year, raising 2.25 million euros, or 2.43 million dollars.

Some experts point out that collecting admission fees didn't lead to a decrease in tourist numbers. But the city plans to continue the testing in a bid to assess the effects.