The Prince's Stone (German: Fürstenstein, Slovene: Knežji kamen) is the reversed base of an ancient Ionic column that played an important role in the ceremony surrounding the installation of the princes of Carantania in the Early Middle Ages. After the incorporation into the Frankish Empire the procedure held in Slovene language was continued as the first part of the coronation of the Dukes of Carinthia, followed by a mass at Maria Saal cathedral and the installation at the Duke's chair, where he swore an oath in German and received the homage of the estates.
The column probably originates from the nearby Roman city of Virunum, established as capital of the Noricum province under the reign of Emperor Claudius (41-54). During the Middle Ages the coat of arms of the Duchy of Carinthia were engraved at its top surface. Till 1862, when it was transferred to the Landhaus provincial assembly at Klagenfurt, it stood northwest of the Kaiserpfalz of Karnburg (Slovene: Krnski grad) in the Zollfeld plain, built by Emperor Arnulf of Carinthia.
The notion of the rulers receiving the power not from God or via inheritance, but from (the representatives of) the people was a notion that was not very common at the time, but it was a notion held by a tribal Slavic society living in peace over hundred years without being invaded.
The ceremony involving this notion was confirmed by several sources, including the medieval reports and the writing of Pope Pius II in 1509. It was also described by Jean Bodin’s in his Treatise on Republican Government (1576) as "unrivaled in the entire world", although there is evidence that the Stone of Scone (now kept beneath King Edward's Chair in Westminster Abbey, although formerly in the ruins of Scone Abbey, Scotland) was used in a similar fashion. See also Lia Fail re. the Irish Kingship of Tara.  An echo of the notion of a stone of kingship is present in European literature in the form of the Arthurian motif of the Siege Perilous - itself derived, ultimately, from ancient Irish conceptions of kingship. 
The peasant, sitting on the Stone, was representing the people during the ceremony and he had to ask in Slovene language: "Who is he, that comes forward?" Those sitting around him had to reply: "He is the prince of the land."
"Is he an upright judge seeking the well-being of the country, is he freeborn and deserving? Is he a foster and defender of the Christian faith?" the representative of the people had to ask them. "He is and he will be", they had to reply.
"By what right can he displace me from this my seat?", he had to ask them and they had to reply: "He will pay you sixty denarii and he will give you your home free and without tribute."
The peasant then had to give the duke a gentle blow on the cheek, after which the duke was allowed to draw his sword, mount the Stone and turn full circle, so as to face ritually in all directions. While this was being done, all had to sing the Slovenian Kyrie and praise God for the gift of a new ruler, in accordance with His divine will. Finally, the ruler had to be placed on horseback and conducted around the Stone three times.
The procedure used as examplary material for US Constitution
In the Thomas Jefferson’s personal copy of the Bodin’s book were found his (Jefferson’s) initials just next to the description of the above ceremony which was then as examplary material used during creation of the US constitution.
The first mention of a sedes Karinthani ducatus in the course of the installation of Herman II of Sponheim in 1161 possibly referred to the Prince's Stone. The ceremony was explicitly described about 1341 by the chronicler John of Viktring in his liber certarum historiarum on the occasion of the coronation of Meinhard II of Gorizia-Tyrol in 1286: when the duke-to-be approached he found a free peasant sitting on the stone. Not before Meinhard had assured him he was worthy to accede to the throne and would be a just ruler would the peasant vacate his position.
The partition of Carinthia after World War I made the Prince's stone a part of the common and therefore disputed Carantanian heritage. When in 2005 the Slovenian government of prime minister Janez Janša decided to depict the Prince's Stone on the national side of the Slovenian 2 cent coin, it caused some consternation in Austria. In 2006 the Carinthian governor Jörg Haider had the stone, that since 1905 had been displayed at the Carinthian State Museum, transferred again to the Heraldic Hall at the Klagenfurt Landhaus.
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- Elizabeth FitzPatrick. Royal Inauguration in Gaelic Ireland c. 1100-1600. ISBN 1-84383-090-6. Page 107.
- Angelique van Engelen (2005) Ancient Slavic Democracy Amounted To Some Magnificent Drama, Global Politician.