On the island of Hsiyu is the Ancient Hsitai Fort, also known as the Li Hung-chang Fort, after the famous Ching Dynasty statesman who was responsible for its construction during the Sino-French War in the last years of the Ching Dynasty.
清光緒年間中法戰後，清廷為防台灣海峽受賊寇侵襲，建立媽宮城及砲台，由李鴻章主事興建，西台古砲台即此遺蹟。這座砲台佔地 8.15 公頃，四周牆垣高築，氣勢森然。牆內壇上有大砲三座，壇下建有隧道，可和砲台互通，儼然是個固若金湯的地下堡壘。