Ogo Castle was built during the Tenmon era (1532-1555) of the late Warring States period by the Ogo clan, who had served for the Uesugi clan during the Warring States period, then for the Hojo clan after the Uesugi clan stated to decline since the Battle of Kawagoe. The Ogo clan moved its bases to Ushigome Castle in Edo (present-day Tokyo) and changed its clan name to the Ushigome clan. In the Siege of Odawara in 1590, when the Hojo clan surrendered to Toyotomi Hideyoshi, Ushigome Castle was dismantled, but the Ogo clan became a retainer of Tokugawa Ieyasu. As Ogo Castle was under direct control of the Hojo clan, the castle was surrendered and finally dismantled in the Edo period. At the present time remain the masugata-mon (the square gate), the dry moats enclosing the gate, the earthworks of Honmaru (the main castle), which reminds us of the days gone by.