We were glad we made a point of spending a night in St Laurent so we could visit here! Very interesting place, and only 6 euros to get in. A guided tour is included, and we were lucky to get an English speaking guide all to ourselves. He was excellent - really enthusiastic about his job too, and gave us loads of little extra information and details we'd never have known otherwise. We learnt all the history of the prison, saw all the old prison buildings and got a feel for what life was like for the prisoners here (pretty awful); I even had my foot shackled to the end of the bed in one of the cells...! Some of the cells still have graffiti on the walls, including 'Papillon' written on the floor in cell 47. It was a more interesting visit than the Iles de Salut, for us, as we learnt a lot more. 100% worth going to, even if you don't speak French (ask for an English speaking guide).