in the southern bailey are "secret exits" or posterns. In Walloon they are "postys". The posty Arlequin led to la Piraille. Via the Posty des Beguines (or of the Gray Sisters) the sisters were able to go to the Saint Elisabeth Hospital to care for the sick. Vehicles could not pass through these postys.
The Posty of Bury is a vaulted passageway that still looks just as primitive. He walked under the gardens of the owners of the blast furnaces in Bury. if you walk down a bit you will see the tower on the right that controlled this passage.
The Rue Saint-Jacques, the name refers to an earlier pilgrimage route, still retains its medieval charm.
In the form of a vaulted tunnel cut into the rock at the eastern end of the second city wall (12th century).
This posty made it possible to go from the upper to the lower city via the alley that runs along the southern ramparts at the foot of the tower and vice versa. Beside each posty stood a guard tower.
The tower with its battlements is a remnant of one of the ten towers that must have been demolished after the battle of the Othée in 1408. By order of the Duke of Burgundy, John the Fearless, the towers had to be demolished.