Machu Picchu, Peru

Machu Picchu was the first major site to impose daily visitor caps—now 2,500 per day via timed-entry slots—but the terraces still pack shoulder-to-shoulder, especially between 10 AM and noon. Each visitor pays $152 for a four-hour window, yet the average walking space per person shrinks to just 3 square meters during peak hours, 40% less than the recommended benchmark for heritage sites. Compared to Mona Lisa’s 15-second viewing sprint, Machu Picchu offers 240 minutes of crowding, making it 960 times longer but with 25% higher physical risk from altitude sickness, as 70% of visitors report symptoms.