The base of the keep tower of Nijo Castle are one of the most important remains of Japanese history and culture. The magnificent five-story, six-story keep once towered over this site. It is said that this keep was built in 1606, in the early Edo period, by the order of Tokugawa Ieyasu, and was a compound, tiered tower-type building transferred from Fushimi Castle. There is another theory that it was a freestanding structure, but in any case, its scale and splendor symbolized the authority of the time. The keep is built on a 20-meter-high stone wall, which was built using the highest technology of the time. The presence of this stone wall tells us how magnificent the castle tower ruins were. Even today, visitors can climb the stone steps to the castle tower, from where they can enjoy a panoramic view of the inner moat, the Honmaru Palace, and the Honmaru Garden. This allows visitors to imagine the majesty of the lost keep. However, the castle tower was destroyed by a fire caused by lightning in 1750, and was never rebuilt. The original castle tower is depicted in the “Rakuchu Rakugai-zu Byobu” and is recorded as a watchtower-shaped five-story tower located in the northwestern part of the castle. This folding screen painting is one of the most valuable documents in memory of the lost keep. Today, the keep itself has been preserved as a symbolic remnant of Nijo Castle's historical value. This stone wall and the ruins of the keep are a symbol of the unification of Japan by Tokugawa Ieyasu, and also a valuable glimpse of Japanese castle architecture. Standing here, visitors can feel the weight of history and the prosperity of the past.