BOGOTA, Colombia -- At the beginning of the decade Roberto was an assistant professor of psychology at the University of Padua in Italy, a certified international chess master and the father of three adolescent children.

Today he spends most of the day in a small hole of an apartment in downtown Bogota, making small drug pipes for sale on the street and smoking basuco, a cheap, viscous mixture of cocaine base and concrete laced with kerosene and sulfuric acid.

Roberto lives in a neighborhood known as El Cartucho, a lawless carnival-hell of a barrio covering 20 squalid blocks and commonly regarded as the most dangerous district in the most dangerous city in one of the most dangerous countries on the planet. It is a drug-dealing and arms-trading nexus in this Andean city, the capital of Colombia. Government presence is almost nonexistent. The police, it is said, are scared to enter.

Yet the Cartucho is three blocks from the presidential palace, the offices of the mayor of Bogota and the capital building. The juxtaposition is a raw display of the government's inability to counter the multiplying social ills affecting the city.

"Here we can wake up when we want to, go to sleep when we want to, and nobody tells us what to do," explains Roberto.

He is a painfully thin man known on the streets as "El Italiano" and "El Profe" -- the Professor. (He asks that his last name not be used.) "The Cartucho isn't necessarily where we want to live," he says. "It's where we can live the way we want to live."

If the current mayor has his way, that cherished way of life may be coming to an end.

Bogota Mayor Enrique Penalosa has a grand plan to raze the Cartucho and plant a park. In recent weeks, Penalosa's office has begun demolishing 28 decaying Cartucho buildings that had been deemed a public nuisance and a threat to public safety. Social-service workers are trying to relocate an estimated 300 people -- 50 families in all -- who have been living in the buildings.

Though not technically part of the urban renovation project, the demolition has been commonly regarded as the launch of the multimillion-dollar park project and the death knell for the neighborhood. It has accordingly stirred up a tremendous show of local feeling among denizens of the neighborhood.

Penalosa had intended to launch the demolition in early March, but when he rolled several dozen riot police and two armored vehicles to the gateway of the Cartucho, residents rose up in resistance, heaving rocks at police and setting alight piles of debris and car tires in the streets.

As the police swiftly retorted with water cannons and tear gas, young bare-chested men ran around with two-by-fours, their T-shirts wrapped around their faces, shouting "Viva, Bolivar!" in homage to the South American liberator.

The police pulled back, and the mayor's office decided to postpone the demolition until officials and the community's de facto leaders could iron out a more civilized plan for carrying out the demolition.

Two weeks later, the first handful of structures, all on the mild fringe of the neighborhood, were knocked down without controversy. "This part is to demonstrate the voluntariness of the people," one of the community leaders explained as the backhoes swung into motion.

A recycling middleman, his name is Ernesto Calderon, but he is called "El Loco" -- "The Crazy One." As police officers milled around and the television cameras recorded the activity, El Loco, sporting a Chicago White Sox cap, lighted a fat marijuana joint, inhaled hugely and smiled.

"We want to show we can work together," he said, "but we haven't accepted anything. If further on there's no dialogue, if they just barge in, then it'll be different."

Fifteen buildings have been knocked down; demolition of the remainder has been rescheduled several times, in part because of the mistrust between the community and the government. Tensions have been running particularly high in recent weeks after the mysterious murders of three community leaders, which led some residents to conjecture that a subversive program of "social cleansing" is under way.

"A hundred, 150 years ago, it was an absolutely beautiful spot," says Diogenes Arrieta, the assistant mayor appointed by Penalosa who oversees the central district that includes the Cartucho.

Indeed, the barrio was once among Bogota's most luxurious addresses. The only reminders of that glorious epoch are the shells of once-elegant colonial homes, their layouts now reconfigured with makeshift walls and jammed like rat warrens with scores of people paying between $1.50 and $3.50 a day to rent floor space the size of walk-in closets.

Perhaps unanswerable is why Colombia's elected officials have allowed the zone to deteriorate to such a state. "It's inexplicable," Arrieta rumbles. "It's the heart of the city."

But in Bogota, criticism of prior mayoralties is cheap. Mayors are restricted to one four-year term, which doesn't help the evolution of long-term projects. Penalosa has less than three years before his term expires, and his plan calls for a park in four, but few people think it's likely he'll have much to show for the Cartucho when his time is up.

Though he admits that the destruction of his neighborhood is politically inevitable, the 44-year-old Roberto bemoans the demise of a unique community.

"They call us disposable, but we have culture here," he says. "A guitarist puts a shoelace where strings should be because that's all he has, but yes, he plays the guitar. And with these throats cooked by basuco, we sing."

The former professor says he wound up in Colombia after killing a man in Italy. He spends most of the day sitting in his sparsely furnished, windowless room.

With him are his three roommates: Ligia, his girlfriend, is an artist who has lived and studied in Atlanta, Barcelona and Washington. Max is a former tae kwon do and swimming champion from Chile who now entertains riders for cash on public buses. John Jairo -- "El Flaco," or "The Skinny Guy" -- is a vaguely bohemian 29-year-old Colombian who peddles Cartucho poetry on the street and steals for a living. They listen intently to Roberto, breaking their concentration only to light up a pipe.

"We want to go on having the right to enjoy our liberty. To throw us out, to relocate us is a crime," Roberto says. "To try to kill the culture of this barrio is a crime.

"There are people here who have heart, people who have feelings," Roberto says. His bony arm envelops the Cartucho with a single sweep. "We are drug addicts, we are considered the scum of society. But we have values, we have dignity."

He pauses and cocks his head, birdlike. "Yes," he intones, "we have dignity."