https://tourism.euskadi.eus/en/cultural-heritage/butron-castle/aa30-12375/en/
There is a public walking path that leads to park grounds where you can walk up next to the castle, but entry into the structure is closed.
https://www.openstreetmap.org/way/42253870 Street view: https://goo.gl/maps/tAPUgzC8LYdt1uLY6
For over three hundred years, from the 16th century onwards, the castle was the scene of non-stop and bloody fights between two sides of Bizkaia's nobility. The lords of Butrón, sheltered in the castle, exerted their power in that area. But Butrón has not always been a castle. In the middle of the 13th century it was a tower-house and the Fifth Lord of Butrón transformed it into a castle in the 14th century.
It owes its present appearance to an almost complete rebuilding begun by Francisco de Cubas (also known as Marqués de Cubas) in 1878.
The castle has a fairy-tale look about it inspired by Bavarian castle models. The present building was created as a hobby for its then owner and to create something which is visually spectacular rather than to produce something in which people could actually live. In fact it would be quite inconvenient as a home as the towers have little useful space and various parts of the castle have exterior connections which are not particularly apt for the wet Basque weather. The building is surrounded by a park which includes palms and exotic plants.
It fell into disuse and was later renovated and opened to the public. This proved to be unsuccessful and the building was closed to visitors although the grounds remained open.
I find it really interesting the difference in attitude in castle preservation in the UK Vs on the continent -- that is, do you build it back and restore the castle, or do you just seek to prevent further damage and keep it in its current state (a la Corfe Castle).
Interesting indeed!