We introduce Larochette to you :

With an area of 15,4 ha and its 2012 inhabitants (registered 2009), Larochette is a multicoloured mix of different nationalities and cultures.
The municipality comprises Larochette, Ernzen, Meysembourg and the farms Goudelt, Leydenbach and Weydert.
The name Larochette comes from the rock on which the castle was built.
Larochette is first mentioned in 1176 under its Latin name Rupe (the rock). Later, around 1182, there will be a German shortform Roketa and another Latin shortform in 1310 Rupella. The actual name of Larochette is first heard in 1317 and it seems as if the lords of that period wanted to clearly make a difference between the French La Roche and the German La Roche. The German name than appears around 1291 as von der Vels, Veilz, Velz, Feltz or Fels. According to the Institut Grand ducal, the Luxemburgish name is “An der Fiels” or “An der Feels”
Link: http://www.institutgrandducal.lu/Joomla/html/placenames_fr.html
 The river is first mentioned in 1378 and 1384 as Erentzin or Erentz and still earlier in Latin as Arantia (876). In this form one can find an ancient celtic word Aar or Ahr meaning water.