A military bunker located near Vlaardingen, Netherlands, identified by the designation 'BP 58 - WN 104 H'. This alphanumeric code is consistent with German WWII organizational terminology (Bau-Pionier / Widerstandsnest) used within the Atlantic Wall fortification system. The Netherlands was extensively fortified by Nazi Germany during the occupation.
However, the specific history, construction details, and function of this particular structure are not confirmed by the provided search results. Its current physical state and accessibility are unknown.