Tsurumaru Castle was the castle of the Shimazu clan, who ruled the Satsuma Domain from the Kamakura period until the Meiji Restoration. The vast grounds were home to the Honmaru, Ninomaru, and Sannomaru, but many of the buildings were lost due to fires and the castle being abandoned. However, parts of the sturdy stone walls and moats still remain, evoking the grandeur of the past. In particular, the remains of the Honmaru offer a spectacular view of Kagoshima city and the majestic Sakurajima.

In 2020, Goromon, the main gate of Tsurumaru Castle, was restored. The magnificent appearance built in the late Edo period has been revived, making it a new symbol of Kagoshima. Goromon is not only a sight to behold, but also its intricate decorations. It is a valuable structure that conveys the grandeur of the castle to the present day, and is loved by many tourists and local residents.

Currently, the "Kagoshima Castle Ruins" have been developed as a historical park, and the Kagoshima Prefectural Historical Materials Center Reimeikan stands within the park. Reimeikan exhibits a wealth of materials related to the history and culture of the Satsuma Domain, providing a deeper understanding of the historical background of Tsurumaru Castle. With the restoration of the Goromon Gate, the historical value and appeal of Tsurumaru Castle Ruins has been further enhanced, making it an important base for communicating the history and culture of Kagoshima.