Trevi Fountain, Rome

Trevi Fountain draws an estimated 1,000 people at any given moment, making it the most densely packed single landmark in Rome—50% more crowded than the typical urban fountain. The coin-throwing ritual alone generates $1.5 million annually, all quietly donated to a supermarket charity, yet the plaza's capacity is 30% smaller than Mount Fuji's summit area. Unlike the regulated peak at #9, this open-air site has no entry fee, leading to peak-hour waits longer than the average European monument and a 25% surge in selfie-related delays.