The architectural point of reference of the Centre is the interior vigilance structure. Located at the heart of the inner square, this high construction, separated from the main floor passage-ways, offers an overall view of Quatre Camins. An interesting feature of the vigilance structure, designed as a special support installation, is its prominent octagonal metal railing ring. An observation tower tops this metal structure and enables correctional officers to carry out occasional surveillance assignments. These subsystems replace surveillance and control normally accomplished by correctional officers from towers on the peripheral wall.
Direct surveillance is done by motorized units.
The Quatre Camins Penitentiary Centre is seen as a real step forward in the design of progressive, efficient and humane correctional institutions in Spain.