In architecture, a folly is a building constructed strictly as a decoration, having none of the usual purposes of housing or sheltering associated with a conventional structure. They originated as decorative accents in parks and estates. "Folly" is used in the sense of fun or light-heartedness, not in the sense of something ill-advised.
Along the river Lek we discovered this landmark made by some unknown artist. Despite it's medieval appearance it wasn't there last time we passed by here. It must have been quit an effort to build this object on a groyne (NL: krib) at the riverbank.