Schloss Heroldeck was built between the years 1911 and 1913 by Ludwig Friedrich Musil Edler von Mollenbruck, owner of a successful paper company in Vienna. Captivated by the beauty of the Millstattersee region, recently made popular by visits of Kaiser Franz Josef, Musil and his British wife chose a steep wooded slope above the lake as the location for their magnificent summer home. The castle was patterned after a chateau in the French Loire valley and named Heroldeck after their youngest son, Harald.
Much of the construction was completed by Italian workmen under the direction of the local Baumeister Anton Lerchbaumer. Little remains of the original interior of the building, though local records indicate the no expense was spared during it's construction.
In 1938 the family were pressured into selling the castle to the Third Reich for just 100,000 reichmarks. The property was earmarked to become a "gauschule" or training school for potential SS officers. An extensive building program was undertaken with the removal of the bell tower, front balcony, several windows and complete reorganistaion of the interior. The following year saw a second building as an accommodation, presently called “the Villa”, constructed on the property to the west of the main castle. By late 1944 the premises were being used to house children from the heavily bombed cities of Klagenfurt & Villach. At the end of hostilities, Schloss Heroldeck was used as a de-briefing center for British army officers, and briefly housed some notable German officers including Field Marshal Albrecht von Kesselring.
By 1947 the property had been turned over to the newly formed Austrian government. Surviving family members were given the opportunity to repurchase the castle, but were financially unable to do so. The building was put to use as a childrens home under local administration.
In 1950, with financial assistance of the Norwegian-European Assistance organization, the castle was developed into a convalescence and retreat center for displaced and under priveleged children. In the following years it would be visited by thousands of children from all over Europe.
When Schloss Heroldeck came up for sale in 1988, Calvary Chapel was approached with the possibility of purchasing the facility for use as a refugee center. As the barriers between East and West Europe began to soften it was clear that the Lord had other plans. The purchase was completed in 1989 and soon groups of volunteer workers arrived and began extensive renovations to prepare the castle for its new purpose, serving the body of Christ as a retreat and Bible study center.