Meṣad Hashavyahu is an ancient fortress on the border of the Iron Age Kingdom of Judah facing the Philistine city of Ashdod near the Mediterranean Sea. It lies 1.7 kilometres (1.1 mi) south of the seaport Yavne-Yam and 7 kilometres (4.3 mi) northwest of the main city of Yavne. The original name of the fort is unknown but was given the name found on several inscribed ostraca recovered at the site. The site covers an area of approximately 1.5 acres (6,100 m2).