Before 1945, Walbrzych was known as Waldenburg, and it was located in Niederschlesien (Lower Silesia), Germany.
According to the city's official website, the early Polish name of the settlement was Lasogród ("forest castle").
The German name Waldenburg (also meaning "forest castle") referred to the castle Nowy Dwór (German: Burg Neuhaus), whose ruins stand south of the city; the name came to be used for the entire settlement. It first appeared in the 15th century, coming from the words Wald (forest) and Berg (mountain) later associated with the castle.
The modern Polish name "Wałbrzych" comes from the German name Walbrich, a late medieval linguistic variation of the older names "Wallenberg" or "Walmberg".
https://en.wikipedia.org/wiki/Wa%C5%82brzych