Odawara-jo Castle / The Short Summary Of Odawarajo
          Odawara-jo Castle was originally a mountaintop castle built on Mt.Hachiman-yama
          by Omori Clan ruled the western part of Sagami-no-kuni (the southern part
          of 
Kanagawa Prefacture). (Some said the Kobayakawa Clan built the castle, and the Omori Clan
          at Suruga-no-kuni seized it in 1416.) There are no specific information
          of the date of construction and the scale of the castle, but it was said
          that the castle might be built in the fifteenth century.
          The Odawara-jo Castle first appeared on the main stage of the Japanese
          History in the Sengoku Periode (the Warring States Period). In 1495, Soun
          Hojo (the founder of Go-Hojo Clan) seized the Odawara Castle in the western
          Kanagawa Prefecture from the Omori Clan with fraud. After Soun moved to
          Odawara, he developed his influence through the area of Kanagawa Prefecture
          actively and aggressively, and his clan had ruled it almost 100 years around
          the Kanto Region. Soun and his descendants reconstructed the castle as
          a flatland-mountain castle and the length of the barriers of the Odawara
          Castle was finally 9 km long, so it was developed as the one of the largest
          castle in the Sengoku Period. Moreover, the 3rd lord Ujiyasu Hojo, the
          grandchild of Soun had completely protected his territory from several
          attackings by Kenshin Uesugi at Echigo-no-kuni, Shingen Takeda at Kai-no-kuni
          and so on, so it was called the impregnable castle. However in 1590, Hideyoshi
          Toyotomi who was the was the Kanpaku Dajo-daijin (the supreme minister
          and chancellor) won the Siege of Odawara, and he buit the Ishigakiyama
          Castle on the way of Tokai-do road near Mt.Hakone, on the west side of
          the Odawara Castle in a night to show his power. The Hojo Clan recognized
          themselves and disappointed at their lesser power to fight against Hideyoshi,
          and gave up, then the Odawara-jo Castle was opened. So the Go-Hojo Clan
          lost the war and ruined. After that, the Odawara-jo castle belonged to
          Ieyasu Tokugawa and the Tokugawa Clan.
          During Edo Period, 
Odawara was of course the castle town of the Odawara-jo Castle, and also it was
          most flourished post town in Tokai-do fifty-three post towns. The lords
          owning the Odawara-jo Castle were given some important roles to protect
          Edo. Odawara was the western barrier of Edo, so the Edo Bakufu chose reliable
          daimyos in hereditary vassalage to the Tokugawa such as Okubo, Abe and
          Inaba.
Now the Odawara-jo Castle is designated as the Historic Landmark by the National Government, and its garden is covered with full of plum blossoms in February every year.
            
            
          参考
            小田原市ホームページ
            小田原市観光協会ホームページ
          神奈川県ホームページ
デジタル大辞林
          ブリタニカ国際大百科事典
          クロニック戦国全史
          ウィッキペディア