In the years after the Civil War, a building was built in the vicinity of Lozoyuela to house prisoners working on the Madrid-Burgos railway works.
This railway line runs through the surrounding area and was a vitally important route at the time.
The prison system during the Franco era, in certain cases, allowed inmates to reduce their sentences in exchange for their efforts in construction.
In this Lozoyuela prison, there were two types of convicts: those with political opinions and those imprisoned for common crimes. Both guys had no contact with each other, even though they worked on the same construction site. In this way, the authorities tried to prevent the political prisoners from spreading their ideas to the rest of their colleagues.
The building at first glance attracts attention. Although the passage of time has deteriorated it, it is still possible to see a robust construction, with thick walls and a considerable height.
The visitor can easily get an idea of what the living and working conditions of those held there were like.
Not far away, following the railway line and also in the Sierra Norte of Madrid, is another building that fulfilled the same function as this Lozoyuela prison: the Dehesa Vieja de Bustarviejo penal detachment.