Much can be said for Prague.

It is a jewel of a city, small enough that most of the most popular bits of it can be seen in a single day, on foot, by the energetic visitor.

It offers castles, museums, dramatic vistas from hilltop perches, a wide river, shopping from one end of the price spectrum to the other and a well-deserved reputation for being inexpensive, when compared to most of Europe’s major cities.

It has culture, history, energy … and one success so complete that it has turned into a negative:

Prague’s exploding popularity has brought so many tourists to the city that the crowds threaten to ruin the place.

We noticed this from the moment of our arrival.

People everywhere.

Prague is being choked by its own success.

Too many people means a degraded experience for tourists as well as residents. It means a temptation for local merchants to rip off tourists in areas where foreigners are thickest and most annoying.

The crowds make regular life difficult (if not impossible) for locals who live (or recently did) in the Old City.

During the peak tourist months, getting around the Old City or over to the Prague Castle is one long grind of ducking and dodging waves of people. Think “New Orleans before Mardi Gras”, with not the same caliber of drinking (thank goodness), and you are getting close.

At times, the crowds can make a visitor feel like he or she is standing in line at a particularly popular Disneyland ride, shuffling forward a few feet at a time.

Tonight, we made a questionable choice: Choosing to buy front-row tickets to a classical music melange (string quartet, soprano soloist, organist) at an impressive church a few steps away from the typically packed Charles Bridge.

It got worse. The city chose tonight to stage a five-kilometer run for women and a 10K for men — starting and ending on the cobblestones of the narrow Old City, and erecting a wall of runners for about two hours as the evening began.

It ought to have taken us no more than 40 minutes to travel via tram from an eastern suburb to the banks of the Voltava and to the site of the concert. It took 70 minutes because of the volume of people in the streets. It struck me that had someone yelled “fire!” in the most-crowded spots, a disastrous stampede could have ensued.

We finally got to the church, a journey ended by the sort of mad rush through streams of people that brought to mind the more fraught moments of Dan Brown novels set in urban centers.

(For the record, it was a fine, one-hour concert, marred only once or twice by the shouts of revelers out on the street.)

Early in the evenings, the crowds skew older, presumably people with money who fill the expensive hotels in the old city and frequent the high-end retailers.

By the time we came out of dinner, the people in the streets had become much younger and much louder, and we bumped into several large, noisy and giddy groups in the midst of pub crawls. (Do those ever end well?) Some of the biggest groups were in residential areas where signs are posted (in English) that noise after 10 p.m. should be kept to a minimum. Ha.

We also noted furtive meetings in the night shadows, perhaps between buyers and sellers of recreational drugs — which are said to be commonplace in the town.

Despite all this, we never felt threatened, even in the sketchier neighborhoods. And, now that I think of it, we rarely saw uniformed police.

Where is Prague going?

The tourists have to be driving the local economy; quite a lot of money is being spent and, goodness knows, the volumes of people are impressive.

It is natural, however, to wonder how many people benefit from the foreigners and their spending. How long can citizens of Prague continue to see their patrimony nearly hidden by international mobs of two- or three-day tourists? When will property costs in the popular areas climb out of reach of the average Prague resident? Or has that already happened?

How long will it be before the first outbreaks of anti-tourist sentiment (such as have been seen in Barcelona and Venice)?

And through it all, even with the crowds, we still found instances of beauty and class and kindness in a marvelous city. It seems perverse, because it may make things worse, sooner … but I recommend seeing Prague as soon as possible — before it becomes hard and angry.