2½ Euros Wiener Schatzkammer

The 2½ euro denomination never circulated in Austria and exists entirely outside the country's normal monetary framework — it was created specifically for collector issues in the late 1990s, before euro adoption, as a way to produce commemorative pieces denominated in the incoming currency. The Wiener Schatzkammer, the Imperial Treasury housed in the Hofburg, holds one of the most intact collections of Habsburg dynastic regalia in existence, including the 10th-century Imperial Crown of the Holy Roman Empire.