Qal'at al-Bahrain is an archaeological site located in Bahrain. It is composed of an artificial mound created by human inhabitants from 2300 BC up to the 1700's. Among other things, it was once the capital of the Dilmun civilization, and served more recently as a Portuguese fort. For these reasons, it was inscribed as a UNESCO World Heritage Site in 2005. Qal'at al–Bahrain( also known as the Bahrain Fort or Portuguese fort) is an archaeological site and historic fort.
It is a typical tell – an artificial mound created by many successive layers of human occupation. The strata of the 300x600-metre tell testify to continuous human presence from about 2300 B.C. to the 16th century A.D. About 25% of the site has been excavated revealing structures of different types: residential, public, commercial, religious and military. They testify to the importance of the site, a trading port, over the centuries. On the top of the 12m high mound, there is the impressive Portuguese fort, which gave the whole site its name, qal'a, meaning fort. The site was the capital of the Dilmun, one of the most important ancient civilizations of the region. It contains the richest remains inventoried of this civilization, which was hitherto only known from written Sumerian references.