ROME » Dapper as always in their bleached white shirts and matching caps, members of Rome’s municipal police force were out on the Spanish Steps one warm autumn day, trolling for offenders.

"Stefano, look! There’s another eater," one officer said to another before sauntering over to a baffled couple who had begun munching on inoffensive-looking meal while sitting on the steps. The culprits, a couple of foreign tourists, had settled down on the landmark, one of Rome’s most famous. In their hands were the offending items: sandwiches.

The officers pounced, and after much waving of hands, the couple wrapped up the sandwiches and slouched away, looking sheepish.

They were in violation — unwittingly, in all probability — of a municipal ordinance that went into force this month. The measure outlaws eating and drinking in areas of "particular historic, artistic, architectonic and cultural value" in Rome’s center, to better protect the city’s monuments, which include landmarks like the Colosseum, the Pantheon and the Spanish Steps. Fines range all the way up to $650 for culinary recidivists.

Italian cities, Rome included, have long enacted ordinances and regulations to protect monuments from ill-mannered tourists (and residents). But after a recent stroll through the city center, where he saw several people making themselves at home, literally, Rome’s mayor, Gianni Alemanno, decided the rules needed toughening.

"There were people camped out, and we weren’t able to move them," said Antonio Gazzellone, the municipal council member responsible for tourism, noting that alcohol may have been involved. The new ordinance, which also outlaws camping or "setting up makeshift beds," will "give monuments back their proper decorum," he said. "Rome needs to be protected, its beauty respected."

But there has already been some grumbling around town.

Recently, a salesclerk named Massimo strode off with his lunch after a police officer sharply blew her whistle until he stopped eating a sandwich on the Spanish Steps.

"It seems to me that the municipal police have more important things to deal with than people eating sandwiches," said Massimo, who asked that his last name not be used because, after all, he had just broken the law.

Others fretted that the ordinance is too broad.

"From now on, a tourist walking around the Colosseum with an ice cream cone will be fined," said Angelo Bonelli, a member of Italy’s Green Party, who flagrantly challenged the ban by eating a sandwich in front of the Pantheon while taunting a municipal police officer.

Rome has passed any number of bans during the past five years, against prostitutes, homeless people and men taking their shirts off in parks to sunbathe, Bonelli noted, often to little effect.

"You can’t govern with bans," he said of Alemanno. "It’s a sign of his inability to control the city."

Many Romans agree. One recent Saturday, a few hundred protesters gathered in a flash mob on the steps leading to City Hall, chomping on pizza and panini as police officers registered the offenders. "Panino is not a crime," one attendee wrote on his Facebook page.

Other Italian cities, where tourists and residents coexist in a delicate balance, have also taken measures to promote civility and good manners. For years it has been illegal in Venice to eat bag lunches while sitting on the steps around St. Mark’s Square, where 25 million tourists converge each year, said Marco Agostini, the city’s director general.

"It’s the one place in Venice that all visitors want to see," he said, "and we can’t have a situation where you have to climb over people eating salami sandwiches."

This summer, Venice — along with the square’s business association — hired eight people to act as "guardians" of St. Mark’s, answering sundry questions, like "Where do I find the Colosseum?" Agostini said, and not only politely informing tourists that the Colosseum is in Rome but also directing them to the gardens just around the corner, where munching outdoors is legal.

In Florence, too, rope cordons went up this summer around the steps of the city’s cathedral, where visitors were asked not to sit. Custodians kept watch from 10 a.m. to 5 p.m. each day, "but in fact, after hours, people went back to sitting there," said Ambra Nepi, the spokeswoman for the Opera di Santa Maria del Fiore, which oversees the cathedral and nearby religious monuments.

Nepi said she understood that Florence could be expensive for some tourists, hence the bag lunches, and that there was a distinct lack of benches in the city center. But some visitors "abused the situation" and sprawled on the cathedral steps to suntan or nap, she said.

"People need to know that after all this is a church," she added. "It’s a way of educating visitors, and it’s not as though we went out with guns."

Gazzellone, Rome’s head of tourism, dismissed concerns that visitors strolling with ice cream or slices of pizza would be fined, "as long as they throw any waste in the trash bins." It’s more a question of civility, he said: "You wouldn’t eat a pizza and drop tomato sauce all over the steps of the White House in Washington."

The ban must be renewed at the end of the year, he said, but that is considered pro forma.

"We’ll see what the results are," he said of the new law. "Personally, I hope it is never applied — because it means that citizens and guests to Rome have understood how to behave. I hope we don’t make a penny — because it means the city is being respected in its beauty."

© 2012 The New York Times Company