Turjak Castle (pronounced [tuˈɾjaːk]; Slovene: grad Turjak or turjaški grad, German: Burg Ursperg, later Burg Auersperg) is a 13th-century castle located above the settlement of Turjak, part of the municipality of Velike Lašče in the Lower Carniola region of Slovenia. The castle is 20 km southeast of Ljubljana and is considered among the most impressive in the area.
The origin of the castle's name is uncertain: local tradition has held that it derives from the extinct wild cattle aurochs (in Slovene, tur). It is more likely a corruption of the name of its founders, the knights Ursberg or Auersperg. The similarity to Turriaco in Italy, also known as Turjak in Slovene, is widely considered coincidental.
The first Turjak castle was built on the site as early as the late 11th century by the knights (later counts) von Auersperg. It may have been extant by 1062, the date the family (specifically Konrad von Auersperg) is first mentioned. In 1140, it was destroyed and burned during a succession struggle between the two heirs of Pilgram II von Auersperg, his son Pilgram IV and his son-in-law Otto von Ortenburg. The castle was held by Pilgram IV, who was defeated.
In 1190 it was rebuilt by count Adolf II von Auersperg, whose son Otto became entangled in a complicated war with the noble houses of von Gortz, Ortenburg, and the Patriarchate of Aquileia, during which the castle was again flattened. Afterward, the site of the first two castles was abandoned in favor of the current one further upslope.
The current castle is first mentioned in 1220. In 1270, Peter and Wolfgang von Auersperg sold it to another branch of the family, only to have it bought back by Balthazar von Auersperg, chancellor of the Holy Roman Empire. In the 14th century, Auersperg owners included Gerhard (1317), and the brothers Friederich, Volkard and Herward. The castle was completely destroyed by the great earthquake of 1511, but was rebuilt in time to successfully resist a furious peasants' revolt in 1515 that laid waste to several other castles in the region. It faced a more serious challenge from Turkish raiders, who undertook major assaults against it in 1491 and 1528, but were repelled both times.