Arato Castle is a historic park located in Chikuma City, Nagano Prefecture, that recreates a mountain castle from the Warring States period. It is said to have been built in 1524 by the Yamada clan, a branch of the Murakami clan, a local clan that once ruled this area. Based on documents and excavations from that time, the main enclosures (main enclosures), the second enclosure, the third enclosure, and the fourth enclosure have been faithfully recreated in the form of a linked mountain castle, allowing visitors to experience the castle's appearance at the time. The castle is also equipped with turrets, gates, and earthworks, allowing visitors to feel the breath of the Warring States period.

The greatest attraction of the castle is the overwhelming view that can be obtained from its location. From the main enclosure and turrets, you can enjoy a 360-degree panoramic view of the majestic flow of the Chikuma River below, the streets of Togura Kamiyamada Onsen town, and even Zenkoji Plain and the Northern Alps in the distance. The view on a clear day is particularly special, and you can look out over the country as if you were a Sengoku warlord. The sunset and night views are also beautiful, and the scenery changes depending on the time of day.

Currently, it has been developed as Chikuma City Shiroyama Historical Park, where you can see the remains of the main citadel, second enclosure, turrets, and other structures.
Although it has been restored, it is a simple mountain castle that does not have a castle tower, so you can get a sense of the atmosphere of the time.

Inside the castle, there is an exhibition room that introduces the history of Arato Castle and excavated items, where you can learn about the lives of people and the battles of the time. It has also been used as a filming location for movies and dramas, so it is a spot that even non-history fans can enjoy.