Jeongjuganseong Castle is located in Incheon, South Korea. It was also called Samanseong Castle. It was built by three children from Dangun. The date of its construction is uncertain, but it is likely that it was built before the Koryo era. This castle holds a lot of information and historical monuments, and you can visit it to learn about it and listen to its history and the history of the battles that took place near it, and you can also walk in the surrounding nature and enjoy its beauty.