The statue of Christ and the Maracana stadium. Rio's poor can't easily afford to visit either one. The city is the host for the 2014 World Cup of soccer. Felipe Dana / Associated Press

Generations of Brazilians have grown up in the Estadio Jornalista Mario Filho, known around the world as the Maracana. Built for the 1950 World Cup and at the time the largest stadium in the world, it became an instant national landmark, a symbol of Brazil's soccer-centric culture.

The stadium, which is likely to host the 2014 World Cup opener and final, is flanked by hills and favelas, the city's notoriously poor slums.

The view of the field from the standing-room general admission area of the Maracana cost just $1.80 not long ago, making it one of the few places Rio's poor residents could afford to go for world-class entertainment.

Not anymore.

That general admission area, known as the geral, has steadily disappeared. Its capacity - some say more than 200,000 crammed in for the 1950 final, a heartbreaking loss to Uruguay - will be just 76,525 when the renovated Maracana reopens in 2013 to host the Confederations Cup, the World Cup's dress rehearsal. Those renovations will cost more than $600 million, but they were not entirely welcomed.

"It's just one reform after another without anyone ever doing any kind of research as to what the people who actually use the stadium want," said Christopher Gaffney, a visiting professor of urbanism at the Federal University in Fluminense in the state of Rio de Janeiro.

Mr. Gaffney is part of a recently formed group of activists called the National Fans' Association. The culture and the history of Brazilian fandom is being swept away, they argue, as stadiums are modernized. "The culture of Brazilian football isn't just one of going to the game and having a hot dog and a beer," he said. "It's active participation in what is a fundamental element of Rio's culture."

As more and more Cariocas, as the locals are known, are priced out of attending games, the National Fans' Association has grown. The organization was created in October and now has 2,700 members.

Luxury boxes, modern seating and safety improvements are reasons Brazil's stadiums are changing as the country prepares to host the World Cup and the 2016 Summer Olympics. They are also likely to increase ticket prices. But the Maracana, a municipal stadium, is also one of the city's revered public spaces. "Do you give up the vitality of the Maracana as a public space, a rare type of space in Rio where you can actually get together people of different social classes?" said Bruno Carvalho, a Rio native who is an assistant professor of Brazilian studies at Princeton University in New Jersey. "What's the price that you pay when you don't allow that to happen?"

Mr. Carvalho said he worries about the Maracana's role as an egalitarian space in a heavily unequal city like Rio. "What could be lost is the nature of the stadium experience as something that cuts across the class segregation of the city as a whole," he said.

Brazilian officials argue that the sorts of stadium renovations that are under way are badly needed. "The dedicated supporter cannot be treated as a second-class citizen in the local stadiums and deserves better viewing conditions, more safety, comfort, as well as access to good catering and other services," said Rodrigo Paiva, a spokesman for the 2014 World Cup's local organizing committee.

The National Fans' Association remains hopeful that the process can be altered.

"Maybe we can make it necessary that they include cultural space, or that they have to at least consult with urban planners or neighborhood associations to see how they should integrate what will basically be white elephants into the urban context," Mr. Gaffney said.

Protected as a historic site, the stadium's structure will remain largely the same concrete bowl millions of Brazilians have known. But inside, the stadium will be unavoidably different.

"It's such a part of the public memory and the very texture of the city that it's hard to imagine it being something else," Mr. Gaffney said. "But now it is. And people are going to have to come to terms with the fact that it is not going to be what it was."