Cities described as overwhelmed by tourism are usually crowded in a handful of streets while remaining quiet elsewhere. The concentration is produced by how visits are organised, not by the number of visitors alone.
Arrival infrastructure sets the starting point
Most visitors enter a city through a small number of stations, ports and terminals, and their first movements radiate from those points.
Cruise arrivals concentrate the effect further, since thousands of people begin and end their visit within the same few hours.
The area within walking distance of these nodes therefore absorbs a disproportionate share of the total, regardless of what else the city offers.
Itineraries converge on the same list
Guidebooks, tour operators and search results largely agree on which sites are essential, and time-limited visitors follow that consensus.
A visitor with one day has no capacity to explore beyond it, so the shorter the average stay, the more concentrated the pattern becomes.
Shorter stays have grown as travel has become cheaper, which is why crowding has intensified faster than total visitor numbers.
Images determine the exact spot
Photographs shared widely identify not just a site but a specific vantage point, and visitors then form queues to stand in that precise position.
This produces intense pressure on locations of no particular historic significance, selected only because they happen to photograph well from one angle.
The effect is fast-moving and unpredictable, since a location can attract crowds within weeks without any change to the place itself.
Local displacement follows the money
Businesses in affected streets shift toward visitor spending because it is higher margin and more reliable, and everyday shops serving residents are gradually priced out of the rents.
Short-term letting reduces residential housing supply in the same areas, which raises rents and accelerates the departure of residents.
The neighbourhood then becomes less interesting to visit, which is the mechanism by which concentrated tourism erodes what attracted people initially.
Management focuses on distribution
Because the problem is distribution rather than volume, responses concentrate on timed entry, capacity limits at specific sites and routing visitors toward less-used areas.
Charging for entry at peak periods shifts some demand into quieter times, though it changes who visits as well as when.
Measures differ substantially between cities and are revised frequently, so what applies in any destination is a matter of current local rules.