JGZ Brdo, the state-owned company managing the mansion along with other high-level protocol venues, said Strmol had impressed international experts, who looked at the level of service, design and inclusion of local content offered by the competing European castles.
Strmol, located 30 km north of Ljubljana, is one of the oldest and best preserved castles in the country and is considered a cultural monument of national importance.
According to JGZ Brdo, Strmol is one of only two Slovenian castles with original equipment.
The mansion's last owners before the estate was nationalized after WWII were Rado and Ksenija Hribar, wealthy industrialists, who often invited the Slovenian elite to social events there.
The Hribars owned the successful Šumi candy producer and weaver Pletenina, each one of key players in their respective markets in the former Yugoslavia. Rado Hribar was also a banker and arts collector.
The Hribars were accused of collaborating with the occupying forces in WWII, even though Hribar was known to have financed the Partisan resistance movement throughout the war. The pair were executed by the then security intelligence forces in January 1944.
Their story inspired the award-winning novel "To noč sem jo videl" (I Saw Her That Night) by acclaimed Slovenian author Drago Jančar.
Kostel Castle opens to the public this week
The STA also report that Kostel Castle, the second biggest castle complex in Slovenia, encompassing a fort and a nearby village, will open to the public on Friday following renovation.
The castle will host an exhibition dedicated to peasant uprisings until autumn. It will also serve as a venue for concerts, theatre shows and workshops.
The renovation works started in the mid-nineties and have reclaimed some of the castle's former glory. The state invested in masonry work and then handed the complex over to the local community for management.
The municipality has invested EUR 400,000 to connect the castle to the electrical grid, build safe access paths, wooden platforms, staircases and railings.
Kostel Castle was a key fort in the Austrian defence against Turkish invasions in the 15th and 16th centuries. It was also a part of a signalling system that used bonfires to raise alarm.
The first written mention of the castle dates back to 1336, when the complex was called Grauenwarth. It is unclear when it was built but estimates indicate that construction likely began around 1200.
The initial towers that were later upgraded to form the castle were built on an ancient fort. The nearby Kostel village is the only still inhabited castle square in Slovenia.