In 1857 Bernadette Soubirous’ family fell on hard times and were forced to move to this dingy former prison, where they lived communally in a room measuring just 16 sq metres. It was while living here that Bernadette stumbled across the Grotte de Massabielle, having been sent out to collect firewood.
There's often a guide around who will tell you (in French) what life was like for the Soubirous family living there.