was aÃÂ Sengoku periodÃÂ yamashiro-styleÃÂ Japanese castleÃÂ located in the Kanaya neighborhood of the city ofÃÂ Shimada,ÃÂ Shizuoka prefecture, Japan. The ruins have been protected as aÃÂ National Historic Site since 1975.
Suwahara Castle is located at the edge of cliff in the northern part of the Makinohara Plateau, commanding the location where theàà Âi Riveràcrosses theààTà Âkaidà  highway. It has an elevation of about 200 meters. At the time the castle was constructed, the river was closer to the cliff face, so that the castle was strategically important for controlling both the highway and the river. Theàinner baileyàof the castle is a square-shaped area, 100 meters on a side, which is backed against a steep cliff. Twoàenclosuresàspread in concentric circles from the inner bailey, each protected by a moat and wall. The second bailey is approximately 100 meters long by 80 meters die, and the third bailey is approximately 200 meters long by 80 meters wide. In the middle of both the second and third bailey is a large semi-circular fort, called an "Umadashi", which is a construct unique to Takeda clan designs. Each "umadashi" is a 40 meter semi-circular wall, protected by a dry moat, with a gate on either end, from which the defenders could protect the flanks of the wall, the gates, and to stage counterattacks. total size of the castle was about 300 meter long and 200 meter wide.
Following the death of the warlordàTakeda Shingen, his sonàTakeda Katsuyoriàattempted to pursue his father's legacy by pursuing a highly aggressive policy againstàMikawa-basedàTokugawa Ieyasu. As part of this campaign, Katsuyori ordered his generalàBaba Nobuharuàto construct a castle at this location in 1573 in order the facilitate the Takeda invasion ofàTà Âtà Âmi Provinceàandàcapture of Takatenjin Castle. It was named after a Suwa shrine brought to this site by the Takeda clan fromàShinano Province, as the Suwaàkamiàwere the tutelaryàkamiàof the Takeda.
In 1575, following their victory at the Battle of Nagashino, the Tokugawa swept through Tà Âtà Âmi Province, and overran Suwahara Castle. The castle was renamed Makino Castle and used as the Tokugawa base of operations against the Takeda in the Siege of Takatenjin Castle in 1581. After Tokugawa clan was relocated to the Kantà  region by Toyotomi Hideyoshi in 1590, Suwahara Castle was abandoned.
Despite having been used for only less than 10 years, original plan of this castle clearly remains. The castle was listed as one of the Continued Top 100 Japanese Castles in 2017. The site is about a 30-minute walk from Kanaya Station on the JR East Tokaido Main Line.