Hisarlaka fortress

Hisarlaka Fortress is an ancient and medieval fortress occupying a hill at 2 kilometres (1.2 mi) to the south-east of Kyustendil, in what is now Bulgaria. Originally constructed by the Romans around 400 AD, it was among the most important castles of the Bulgarian Empire in the Middle Ages before it was partially destroyed by the Ottomans in the 15th century. Hisarlaka Fortress was the administrative and religious center of the region from the 5th to the 15th centuries. The expansive fortress was constructed over ten centuries by different rulers.