Sarmizegetusa Regia, also Sarmisegetusa, Sarmisegethusa, Sarmisegethuza, Ζαρμιζεγεθούσα or Ζερμιζεγεθούση, was the capital and the most important military, religious and political centre of the Dacians before the wars with the Roman Empire. Erected on top of a 1200 m high mountain, the fortress, comprising six citadels, was the core of a strategic defensive system in the Orăștie Mountains.
Sarmizegetusa Regia should not be confused with Ulpia Traiana Sarmizegetusa, the Roman capital of Dacia built by Roman Emperor Trajan some 40 km away, which was not the Dacian capital. Sarmizegetusa Ulpia was discovered earlier, was known already in the early 1900s, and was initially mistaken for the Dacian capital, a confusion which led to incorrect conclusions being made regarding the military history and organization of the Dacians.