Buchberg Castle lies three kilometres south of Gars am Kamp on the crest of a rock on the right bank of the river Kamp. Staggered across several different levels behind an arrangement of ornamental gardens, the multipart complex has been shaped by numerous construction phases ranging from the 12th to the 20th century.

The first documentary evidence related to Buchberg Castle dates from between 1140 and 1170, when a Heinrich von Puechperg is recorded as being a ministerialis of the burgrave of Gars. On the crest of a rock, he constructs a fortified house surrounded by a protective enclosing wall. Official deeds mention his two sons, Hugo and Otto, in connection with their participation in the Crusades to the Holy Land. Another reference to this is the fact that the chapel is dedicated to the Finding of the True Cross; a castle chaplain appears in the records as early as 1197.

Evidence of these ‘early Buchbergs’ continues into the early 13th century. Then the castle passes into the ownership of the Falkenberg family. Its first representative, Albero, and his descendants call themselves Buchbergs. Due to financial difficulties, half of the castle is ceded to the Habsburgs in 1330. The other half is purchased in 1339 by the Messrs von Winkl. A study by Evelyn Brugger describes in detail the challenging financial and complicated property situation in the early 14th century. From 1356 to the mid-15th century, the noble family owns Stockhorn Castle and the seigniory of Buchberg. From 1588 to 1592, the owner is registered as Mathias Teufel, to whom Gars Castle also belongs. A description in an appraisal drawn up in 1585 conveys the impression of a medieval fortress. Evidently, it has fallen short of contemporary living standards, since the document states: ‘Firstly Puechperg [Buchberg] Castle, which though with its grandeur and freedom lies at quite a height and on a rock next to the Khamph [river Kamp], inside is nevertheless equipped with bad and few rooms. Otherwise, however, surrounded and enclosed by a thick castle wall and two solid towers built of stone.’

Hans Georg von Kuefstein purchases Buchberg Castle and its estate from Matthias Teufel in 1592. From 1612 to 1624/27 they are the property of his son, Hans Ludwig von Kuefstein. In this period, the medieval fortress complex undergoes extensive conversion work. It acquires its present-day, Early Baroque, castle-like appearance, which G. M. Vischer captured in an engraving. The arms of Hans Ludwig are borne by two imposing, Early Baroque portals in the inner courtyard of the castle.

A survey carried out in 1625 in the context of the sale of the Buchberg seigniory to the Schifer family conveys the great transformation effected by the conversion. The text speaks of a castle ‘which lies on a hard rock, and next to a handsome, graceful and very well-situated home with approximately 40 chambers, a beautiful castle chapel, balconies and small pleasure gardens’ and where one can also see ‘a peculiar, bouncing pipe of water, flowing into all three courtyards and with special fish holders everywhere; with other good amenities, both practical and diverting, especially the newly started and mostly executed pleasure gardens; below are strong, double arches and grottos in which the residual water from the castle is channelled for pleasure and need, as one and another reveals itself to the eye.’ Large sections of the medieval structure are integrated into this modern conversion.

In the 18th century, the site undergoes only minimal alterations. Its owners change rapidly due to inheritance or sale. They include the families Pollheim, Auersperg, Collalto, Rottal, Rummel and Stak.

In 1823 Carl Croy purchases Buchberg Castle and its estate, expanding the property in 1826 by acquiring the neighbouring seigniory of Gars. Both estates remain in the family’s possession until 1965. A watercolour in the style of Thomas Ender from around 1830 shows the minimal changes made to the east side since the picture from 1672: the main gateway in the barbican is missing in comparison with Vischer’s engraving and the finial on the tower now has a simple geometric shape in accordance with the formal canon of the Biedermeier period. The uppermost accessible level of the tower dates from the era around 1500. The crenellation-like edgings are in fact the supports of the roof truss that was probably constructed in the early 19th century and that survived until around 1880. In this watercolour, the belltower of the chapel still features a Baroque onion dome.

An important stage of the castle’s structural development begins under Alexander Croy. In 1873 he commissions the architect Ludwig Wächtler with redesigning the medieval chapel in the historicist style; it is reconsecrated in 1874. Its painted interior decoration with an elaborate Passion cycle in the barrel vault is executed after a design by Franz Jobst. Today, the original 15th-century altar triptych, which – in accordance with the chapel’s dedication – shows the Finding of the True Cross, is in the possession of the Croy family. In 1989, the artist JORRIT TORNQUIST replaces the missing altarpieces with a contemporary design.

In the course of the historicization by Alexander Croy, the barbican’s outbuildings are demolished and replaced with a courtyard planted with lime trees featuring an elevated, round turret. It was presumably in the course of this construction work that the entrance tower was renovated; this is indicated by a dendrochronological analysis of the timber framework.

On the cadastral plan of 1868, it is already possible to identify a park in the style of an English landscape garden. In the early 20th century, terraced ornamental gardens are created on the east side. Inside, the residential structure of the castle is modernized: staircases are installed and the interiors are redecorated. Adjoining the northern bailey, the so-called New Castle is constructed around 1912/14 with a residential and a kitchen storey.

In 1965 the Bogner family purchases the Buchberg estate. In 1979 Dieter and Gertraud Bogner found the Kunstraum Buchberg in its castle.