Kingdom of Romkerhall
Located in Okertal, a narrow valley surrounded by high mountains within the slate-and-granite highland region of Oberharz (Upper Harz), in Germany's Niedersachsen (Lower Saxony) state. Romkerhall, named after a small river, the Romke, is in the administrative district of Braunschweig and the county of Goslar. Originally a hunting lodge, it was built in the 19th century by King George V, and the property belonged to his Kingdom of Hanover. He refused to support Prussia in the Austro-Prussian War (1866), and consequently lost his kingship. This monarchy was annexed in 1871 by Prussia as a province, until the German Empire came to an end in 1918. The current owner is Baron Walter Lechner (a former architect), who purchased this former princely estate after a fire. He claims that the surrounding territory was forgotten about and never formally attached to a particular parish; the mistake was repeated in 1970, whence it again went unassigned after a general reformation/regional reorganization of the parishes. He took advantage of this opportunity by attracting Princess Erina von Sachsen, Duchess to Saxonia, to his miniscule piece of municipality-free, independent land. She, married to Prince Thimo (grandchild of the last king of Saxony, Friedrich-August III, who was deposed in the aftermath of World War I), was enthroned as acting Queen in 1988; on that same day, his establishment was proclaimed the “world's smallest Kingdom”. Since then, Romkerhall has been the cause of continuous quarrels between the Baron and the German government and its aristocracy. In terms of marketing, the Baron attempts to lure tourists to the premises by offering to host several types of services for the celebration of special occasions (birthdays, anniversaries, baptisms, confirmations), not the least of which are fancy weddings, conducted in Romkerhall's audience hall. The Baron sells/confers titles of nobility to worthy individuals; and he has received some publicity by allegedly listing, as a steeply price-tagged gag, his Königreich on eBay first for $37 million, and then for the even more exorbitant sum of $60 million.

Their Web-site, where a few of the coins can be seen, is:
http://www.koenigreich-romkerhall.de/
 
 
I purchased their ½, 1, 5, and 10 Königsthaler tin set of coins, each having a diameter of 30mm and thickness of 2 mm (though dated 1988, they were actually struck in 2005, by the firm Kunst- und Gewerbering, in Halsbrücke). There is as well a Queen Erina commemorative Thaler, known as Gedenkthaler (though dated 1998, actually handmade by Baron Christian Gross in 2005). All these pieces are available in issues of tin, silver, 24-karat gold-plated silver, and pure gold. These coins can be used within the Kingdom (Hotel, Restaurant, Touristshop etc.) as legal tender.
 

 
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Chiefa Coins