The neighborhood still called the "castle's yard" today designated the first core of Thionville. Originally, this small terrace at the edge of the Moselle was chosen to house a Carolingian domain, called "palacio publico", mentioned in 770. The Counts of Luxembourg built a castle there in the 11th century from which remain the dunjeon and the flea tower (which is a museum today).
Private mensions built by the town's provost-marshals, the Eltz and the Raville, can be seen.
Finally, the Clarisses settled there in the 17th century.