The walls are meant to prevent Rio de Janeiro’s shantytowns, known as favelas, from expanding into the city’s forested hillsides. But residents of these slums, which are among the poorest in the world, feel like they’re being jailed.

The walls dubbed ‘ecobarriers’ by Rio state government are supposed to help preserve the city’s Atlantic rain forest. The government hired contractors to construct the 10-foot cinderblock wall as part of a beautification project that Rio officials hope will help the city in its bid to host the 2016 Summer Olympics. In addition to the wall, officials plan to pave roads, install parks and demolish homes built inside the forests.

Favela residents see the wall as just another attempt to increase the disparity between the poor, violent, heavily populated slums and the ritzy beachside neighborhoods located just steps away. About 20 percent of Rio’s residents live in favelas, but most Brazilians pretend like these people don’t even exist and the wall deepens that sense of segregation. What the Rio government calls environmental protection and beautification, slum residents and human rights advocates call apartheid.

"They want to cage us like animals," says Antonio Marques, who lives in the Rocinha favela.

The government denies any intent to segregate people. Ícaro Moreno Júnior, the head of Rio's municipal-works company and overseer of the project, says "Someone has to wake up. In all of Latin America the forests are being invaded and destroyed.”

Local leaders have asked for footpaths instead of walls, so favela residents won’t feel trapped inside and can still enjoy access to nature. Officials are reportedly considering alternatives.