But there is more to this tableau of extreme urbanism than meets the eye.

Many of the teenagers in the Alameda, on the edge of Mexico City´s Historic Center, are indigenous peoples, just weeks or months removed from rural pueblos.

They are part of a massive movement of minority indigenous Mexicans from the countryside into Mexico City, a migration within the country´s borders that is transforming centuries-old living patterns.

For these youths from ethnic and Indian groups that pre-date the Spanish conquistadors, the adoption of hyper-urban styles of dress can be a survival strategy.

"They face so much discrimination when they come to the city, that´s why they transform themselves," said Pedro González, a 38-year-old university student and migrant advocate who left Oaxaca for Mexico City when he was 16.

"They are looking for a type of identity, because they say, ´just by myself, I´m going to die.´"

NEW ARRIVALS

Alejo Martínez, a 16-year-old from a small village in the northern state of San Luis Potosí, arrived in Mexico City earlier this month and is already putting together his urban armor: a Slipknot bandana, black T-shirt and dyed blond hair.

Although he had only been in town about a week, he knew the Alameda was the place to be on Sundays.

"We just come here to have fun - it´s better than being locked inside all day," he said. "Mexico City is pretty big. I don´t know too much about it yet."

Federico Gama, a Mexico City photojournalist, has been photographing and studying the indigenous punk and goth movement for more than two years. He said that while migration into Mexico City is nothing new - it´s been happening in large waves since the 1940´s - what has changed is the more defiant attitudes among indigenous teenagers.

Many come to work in the city´s construction trade, which has been booming since the mid 1990´s, often sleeping at construction sites. Their first introduction to city of 20 million, experts say, is one of rejection, name-calling and mockery.

"When they come here, these young guys detect that and say they don´t want that image," Gama said. "With this clothing, they are saying all they can´t say with words: ´I´m urban and I´m a part of this city. This city is not going to crush me.´"

Officials say there are about 1 million indigenous residents in Mexico City, or 5 percent of the population. The majority of Mexicans are mestizos - a mix of Spanish and Indian or indigenous ancestry.

Although official statistics are scarce, migrant advocates say they are arriving in increasing numbers, driven by the same factors that have spurred mass migration to the United States.

According to the 2000 census, the average income of indigenous workers in the city is more than double their rural counterparts.

The decision to migrate to Mexico City rather than to the United States is determined by well-worn migration patterns, but also by a rather simple calculus: while the United States offers better wages, it´s also much more dangerous to reach. Mexico City is a safer, but often less well paying, alternative.

In recent years, many migrants to Mexico City have used the capital as a staging area before moving to the United States.

Mexico City is also home to nearly 100 original indigenous communities, groupings that have existed in the Valley of Mexico since Mexico City was the Aztec island kingdom of Tenochtitlan.

UNFRIENDLY METROPOLIS

City officials have acknowledged that Mexico City is an unwelcoming place for migrants.

"The indigenous find in the city a hostile environment that with alarming frequency discriminates against them and considers them inferior and backwards," city officials wrote in a recent report.

Last year city officials agreed to create a department for indigenous affairs, but advocates say the city has much to do especially in terms of educating the thousands of indigenous children who don´t attend school.

Experts say that indigenous teens who migrate to the city face a painful identity dilemma.

The worldview that they learned in their villages - often a system of collective and communal living - has no place in the bustle of one of the world´s largest cities.

"For many this implies two roads," González said. "Either you hide and forget your culture, or you try to reinforce it."

In some ways, the punks in the Alameda are combining city and village values. While they dress in highly individualistic styles, they have formed a kind of collective space where they can share survival tips and reinforce each other´s confidence.

But despite their punk, gothic or hip hop inspired attire, they are not connected to traditional subcultures. On Sundays many gather to go to underground clubs that play cumbias and other Mexican regional music.

On a recent Sunday afternoon, one storefront club was the improbable scene of a trio of punks in spiky hair twirling their partners to traditional music.

And despite their often fierce appearance, they are not hardened city folk.

On a recent Sunday, a teenager from Veracruz, dressed in a menacing black outfit covered in metal spikes, virtually melted when approached by an interviewer, whispering answers and staring at the ground.

Some observers say the new urban stylings could signal a disruption in values.

Gama, the photographer, said the new styles of dress represent a fundamental shift - whereas indigenous youth used to send the money they make back to their villages, they are beginning to spend it on themselves.

And that could have far reaching consequences, said Guadalupe Martínez, coordinator of the Assembly of Indigenous Migrants in Mexico City.

"When they arrive in the city it´s an enormous shock and other kids your age are telling you, ´why are you sending money back home?´" she said. "You run the risk of forgetting your identity and incorporating yourself into this city."

Martínez said the act of sending money back to the village is fundamental to the indigenous migrant experience. Failure to do so could mean rejection when the migrant returns.

"The community expects those that leave to send a certain quantity back," she said. "That´s the only way they will respect your house, your lands."