The first lord of Mersch, Theodoric, appears in a 1232 text as: "Miles, dictus of Maresch, dapifer comitissae de Lucenburch”. He is a knight and vassal of Countess Ermesinde. In this document a "Turris” is mentioned. This tower is most likely the keep. The alignments of the stones reveal two construction periods.
Theodoric was to build a new castle with a moat. The Burgundian troops stormed this castle and burned it down. In 1574, the owners drew up a plan for building a new castle. Its dimensions were 61 by 70 metres, the moat was 11 metres wide, the enclosure wall was 1.35 metres thick and was flanked by seven towers. When Paul von der Veltz became sole owner in 1585 he fitted large windows in the keep, transforming the building into comfortable living accommodation.
In 1603, during the conflict between the King of Spain (who was also Duke of Luxembourg) and the Spanish Netherlands, the castle was burnt down again.
Towards the end of the 17th Century, the then lord, Count Jean Frederic von Elter rebuilt the castle. His coat of arms, at the castle entrance, is testimony of this restoration.
In 1717, the castle chapel was re-consecrated. The last noble family to own the estate, the Sonnenberg-Reinach family, sold the property in 1898 to a merchant by the name of Schwartz-Hallinger.
In 1930 the then owner Mr. Uhres, undertook a restoration, and in 1938 the structure was converted into a youth hostel.
The town council acquired the castle in 1957 and three years later it was handed over to the state. As soon as 1988, in an exchange between the state and the council, the castle once again came into the council's ownership. The renovated building became the town hall in 1993.
The castle is the town hall of Mersch; for this reason it is not accessible to the public.
As you walk in, the chapel -consecrated in 1717- is on your right. The keep in front of you was built in several construction periods.
The interior of the tower was converted by Paul von der Veltz and Apollonia von Kerpen in the late 16th Century. Fine, ornate fan vaults decorate the ground and first floor ceilings.
The imposing hall of knights which occupies the whole second floor houses a beautiful fireplace featuring the coat of arms of both aforementioned owners while the coats of arms of 16 of their noble ancestors adorn this hall.