The Maria Theresa thaler (MTT) is a silver bullion-coin that has been used in world trade continuously since it was first minted in 1751. It was named after Empress Maria Theresa, who ruled Austria, Hungary, and Bohemia from 1740 to 1780.
Since 1780, the coin has always been dated 1780. On September 19, 1857, Emperor Francis Joseph of Austria declared the Maria Theresa Taler to be an official trade coinage. A little over a year later, on October 31, 1858, the Maria Theresa Taler lost its status as currency in Austria.
The following mints have struck MTTs: Birmingham, Bombay, Brussels, London, Paris, Rome and Utrecht, in addition to the Habsburg mints in Günzburg, Hall, Karlsburg, Kremnica, Milan, Prague and Vienna. Between 1751 and 2000, some 389 million were minted. These different mints distinguished their issues by slight alterations to the saltire, or flower symbol, which looks like an X, at the top left of the reverse side of the coin. In 1946, the Vienna Mint rescinded any rights of foreign governments to issue such copies; subsequently, the Vienna Mint has produced over 49 million MTTs.