Château de la Tournelle

The Château de la Tournelle was a small fortress along the southern bank of the Seine in Paris.

La Tournelle, meaning "the turret", was well known to Parisians as a "comfortable" prison for galley slaves. This was thanks to the charitable priest Saint, who used public charity to support the slaves. During the September Massacres of 1792 however, the 63 convicts inside the prison were killed by drunken revolutionaries. Radical political figures such as Jean-Paul Marat had called for the deaths of the prisoners, who were mistaken for dangerous counter-revolutionaries.

Reference

 * Assassin's Creed: Unity