Also called Eastern Fort Castle, Siyu Eastern Fort is located in Waian Village, Siyu Township, and is a fort supervised and constructed by Liu Ming-Chuan in the 13th year of the reign of Qing Emperor Guangxu. At that time, western forts were introduced for military defense purpose. It faces northward and played a guarding function in many battles especially there is an observatory at the east outside of the castle. East West now has been listed as a Class A heritage, full of historical significance, and is a famous attraction of Penghu.