In the Roman era, a fortified tower guarded the crossing of two Roman roads that met at the site of Luxembourg city. Through an exchange treaty with the abbey of Saint Maximin in Trier in 963, Siegfried I of the Ardennes, a close relative of King Louis II of France and Emperor Otto the Great, acquired the feudal lands of Luxembourg. Siegfried built his castle, named ''Lucilinburhuc'' ("small castle"), on the Bock ''Fiels'' ("rock"), mentioned for the first time in the aforementioned exchange treaty.