The first in a new generation of high-security prisons has opened in Brazil, in an attempt to stop gang leaders operating from behind bars.
The government hopes to crack down on gang activity within prisons
The new facility in Catanduvas in the state of Parana will house 208 of the most dangerous prisoners in single cells and under constant surveillance.
A month ago, gang leaders inside jails unleashed a week of unprecedented chaos on the city of Sao Paulo.
At least 120 people died in violence sparked by a dispute over conditions.
The violence was organised by leaders of a gang known as the First Command of the Capital (PCC), whose leaders almost certainly had access to mobile phones.
Their supporters set fire to buses and mounted brazen attacks on police, who responded with a ruthless crackdown.
Authorities are hoping five new prisons will go some way to denying gang leaders the chance to operate from behind bars.
At present they achieve this by bribing prison guards and using their lawyers as conduits to the outside world.
In the new federal prisons, inmates will be held in individual cells under surveillance by some 200 video cameras, which will relay images not only to the prison authorities but to federal police and to the National Penitentiary Department (Depen) in the capital Brasilia.
Guards will wear clip microphones so their conversations with prisoners can be recorded, and x-ray machines will be used to detect guns, explosives and drugs.
Authorities concede the numbers of prisoners held in these jails will make up only a tiny proportion of the total prison population and will not in themselves provide a solution.
"But they will be fundamental in helping state authorities to dismantle organised crime inside the penitentiary system," Depen director Mauricio Kuehne told Brazilian news website Folha Online.
"The basic criterion is not to think in terms of the quantity of prisoners they will house, but the danger they pose and the isolation of negative leaderships."
The BBC's Simon Watts says Brazilian officials also hope the new prisons will help them tackle two other problems with the country's jails: riots, often between rival gangs, and escape bids - which frequently get help from guards.
But there is one potential problem, our correspondent says. The Sao Paulo violence was sparked by a dispute over the detention conditions of gang leaders, and it is unlikely any gang commander will go quietly to the federal government's new jails.