Karasawa Castle or Karasawayama Castle was originally built in 927 by Fujiwara no Hidesato, and Renovated in 1491 by Sano Moritsuna, of the. It was a mountain-top castle, and one of the main castles of the Kanto area, Honshu, Japan. It is sited on the border of Kanto plain and northern mountain areas. and sat next to Sano, the corresponding castle town during the Edo period. Over a period of time, the Sano clan expanded their control over the area, and gradually built up the castle. At its peak, it was a substantial castle, commanding a mountaintop position. During the 16th century, the powerful Warlord, Kenshin Uesugi, lord of Kasugayama Castle moved into the area, and took over landholdings of some of the smaller clans. However, in so doing, he had to travel quite far, and was also being attacked by the Hojo clan. The castle saw most conflict in this period. Under the leadership of, the castle withstood attacks by Kenshin Uesugi. At one point, Masatsuna allied with Kenshin, but eventually he broke free, regaining independence for the castle and for the Sano clan. The Uesugi clan attacked the castle 10 times during the Sengoku Period - a large amount of castle attacks, in a short time period. Toyotomi Hideyoshi conducted a campaign against the Hojo clan, and the Sano supported Hideyoshi. At the time, the Sano were on good terms with the Hojo, but Hideyoshi removed them from the castle. At the battle of Sekigahara the Sano clan sided with Tokugawa. The story goes that after one of the early Fires in Edo, the Sano clan could see the fire down in the city from their mountaintop. The clan sent their condolences to Edo for the unfortunate event. Allegedly, the Emperor was unimpressed that the Sano clan castle look down on Edo, and told them they would have to remove it. Whatever the reason, the clan rebuilt their castle lower down the hill, in a nearby but different position, and this new castle was named Sano Castle.
Current site
There are walls and a well on site, but no buildings except. It is one of the closest castle ruins to Tokyo.
