Haasberg mansion, Baroque manor house in Planina, Slovenia

Haasberg mansion is a baroque-style manor house near Planina in the Municipality of Postojna. The building displays rich architectural details and generous proportions that were typical for wealthy families of its era.

The Eggenbergs built a Renaissance mansion after 1614 beside the old Planina castle. In 1716 Maria Charlotte Eggenberg sold it to Johann Caspar Cobenzl, who had Carlo Martinuzzi rebuild it as a four-storey baroque palace between 1717 and 1723. The Windischgrätz family, owners from 1846, added a brick storey. Partisans burned the palace on 27 March 1944.

The Cobenzl family kept a picture gallery here: an inventory of 1770 lists 119 paintings, including two works attributed to Rubens, portraits, saints and still lifes. A library held rare manuscripts, imperial correspondence and Enlightenment scientific works. A former employee recalled a Dürer painting above the balcony room and a depiction of the Roman entry into Jerusalem over four metres long.

The estate sits in a rural setting and is easily reached by local roads for those wanting to explore the area. The location allows for a walk through the countryside around Planina and the Municipality of Postojna.

The 1770 inventory of the Cobenzl art collection listed 119 paintings at the mansion, including two works attributed to Rubens. A later account by a pre-war employee also mentions a Dürer painting over four metres long depicting the Roman entry into Jerusalem.