Looking at this, you have to wonder whether 'Mad King Ludwig' was quite as mad as some would have you believe.  Certainly, to want a castle as beautiful as his New Stone Swan isn't a sign of madness.  That he didn't finish it... that's crazy.
This castle still belongs to the Wittelsbach family which ruled Bavaria for over 700 years before the Austro-Prussian War brought their reign to an end (1866: they backed Austria; Prussia won).  It is currently leased to Bavaria for 200 years, in part to pay off the debt that Ludwig II incurred having it built.  It is said that the Wittelsbachs can hardly wait for 2120 when the lease expires.  To preserve their property rights, the family does not allow unauthorized photographs of the inside.  I don't blame them.  I wouldn't, either.
Only 15 rooms were ever rendered 'livable', and after Ludwig's mysterious death by drowning in a nearby lake, no further work has been done to complete it although maintenance still continues as you can see in this picture.  Ludwig virtually bankrupted the Wittelsbachs with this and two other castles he had built.  Guided tours of the 15 finished rooms are conducted every day in several languages.