Takeda Castle is a mountain castle built in 1441. The castle was in a strategic location between northern and southern Hyogo Prefecture, which were once separate kingdoms. Eventually it was taken over by the Hideyoshi and after being transferred between other lords it eventually was abandoned in 1600 after the suicide of the last lord, Hirohide Akamatsu.
No structures remain but that doesn't make these ruins any less spectacular. The castle walls are well-preserved and its position as a mountaintop castle make it even more impressive. It is said to be best when there is fog around the castle to make it appear like its floating in the clouds.
The hike to the castle is steep and takes about 35 minutes, but it builds up anticipation and is well worth the effort. These ruins are listed as one of the top 100 castles in Japan.
Asago is served by JR Railway. Most of its stations are located on the Bantan Line, which runs from Himeji Station to Wadayama Station (in Asago). Wadayama Station connects the Bantan Line with the San-in Main Line. Yanase Station is located on the San-in Main Line.
The stations in Asago with some nearby sites are:
-Ikuno Station (Silver Mine sites)
-Takeda Station (Takeda Castle Ruins, Teramachi Street, Ritsuun-kyo Valley)
-Wadayama Station (Okanoyu Onsen)
-Yanase Station (Gakuonji Temple)
From Osaka and Kobe, you can travel to Himeji and transfer to the Bantan Line. Alternatively, you can take the Limited Express Hamakaze to Teramae and change trains there.
From Kyoto it is better to head north to Fukuchiyama and change to the San-in Main Line. From there you can go to Wadayama Station and switch to the Bantan Line (or stop in Wadayama if that's your destination). Limited Express Trains can also be used from Kyoto to shorten travel time.