At number one (by a considerable margin) is Vatican City, a minuscule city-state surrounded by Rome. Dominated by St Peter's Square (pictured) and Basilica, Vatican City is the world’s smallest country and serves as the headquarters of the Roman Catholic Church.

Vatican City’s population officially stands at 882, and 2024 visitor numbers reached a whopping 6.8 million – a ratio of 7,709.8 visitors per local. Early morning is the best time to avoid the tour groups, with Sunday’s noon prayer, Catholic holidays and Wednesday’s Papal Audience drawing large crowds.

Now check out the best and worst times to visit Europe's most popular destinations

Ranked: The most overcrowded countries in the world