The Dacian Fortresses are a series of ancient military structures located in present-day Romania. Built during the reign of King Decebalus in the 1st century AD, these fortifications were designed to protect the Dacian people from invasions, particularly from the Roman Empire. The fortresses are strategically placed on mountain tops and cliffs, utilizing natural landscapes for defense. These fortresses are recognized for their impressive stone walls and complex layouts, which include towers and gates. In 1999, the Dacian Fortresses of the Orăștie Mountains were designated a UNESCO World Heritage Site, highlighting their historical significance and architectural ingenuity.