The Qal'at al-Bahrain (in Arabic: قلعة البحرين‎, also known as the Bahrain Fort or Fort of Bahrain and previously as the Portugal Fort (Qal'at al Portugal) is an archaeological site located in Bahrain, on the Arabian Peninsula. Archaeological excavations carried out since 1954 have unearthed antiquaries from an artificial mound of 12 m height containing seven stratified layers, created by various occupants from 2300 BC up to the 18th century, including Kassites, Portuguese and Persians. It was once the capital of the Dilmun civilization and was inscribed as a UNESCO World Heritage Site in 2005.

The archaeological finds unearthed in the fort reveal much about the history of the country. The area is believed to have been occupied for some 5000 years and contains a valuable insight into the copper and Bronze Ages of Bahrain. The first Bahrain Fort was built around three thousand years ago, on the northeastern tip of Bahrain Island. The present fort dates from the sixth century AD. The capital of the Dilmun civilization, Dilmun was known as the "land of immortality" and the ancestral place of Sumerians, a place where the Gods met.