Ruins of Takeda Castle
"The ruins of Takeda Castle" are located at the peak of Mt. Kojo in the city of Asago. On particularly foggy mornings, the base of the mountain becomes invisible and the castle seems to be floating in air. This mystical scene is where the nickname "Castle in the Sky" comes from and it has also appeared in the movie "Kagemusha" directed by Akira Kurosawa.
If you're lucky, you may be able to see the ruins floating in a sea of mist from the Ritsuunkyo viewing deck at the time of sunrise in the months of October and November.