It is quite extraordinary that the Sovereign Military Order of Malta, better known as the Order of St John, which originated in Palestine before the Crusades, is still in existence after almost a thousand years. The Order of St John no longer has a military function, as it had in the Holy Land, Rhodes and Malta, but has gone back to its original mission of offering medical assistance and tending to those in need.

Few people would know today that the Order, which is a sovereign institution based in Rome, issues its own coins and stamps. The 700-year minting history of the Order is the subject of a special exhibition entitled, The coinage of the Order of St John: between Rhodes, Malta and Rome. The exhibition brings together a selection of coins that gives visitors an overview of the output of the Order's mints in Rhodes, Malta and Rome.

The Order of St John originated around the year 1070 as a hospice set up by some Amalfitan merchants for the succour of pilgrims in Jerusalem. The hospice attracted significant donations of land, property and money especially after the conquest of Jerusalem by the crusaders in 1099. During the 12th century the Hospitallers evolved into a chivalric order entrusted with the defence of the Holy Land.

It was only when the Order of St John became the sovereign master of Rhodes in 1309/10 that it minted its first silver coin known as grosso. Grand Master Helion the Villeneuve (1319-46) replaced it with a new silver coin, the gigliato, while Dieudonne de Gozon (1346-53) issued the Order's first gold coin based on the Venetian zecchino. The zecchino became the standard gold coin of the Order and its imagery remained basically unchanged for the next 300 years. The zecchino was the only coin, which after the loss of Rhodes in 1522, continued to be minted by the Order in Malta after 1530.

On 24 March 1530, after prolonged and difficult negotiations, Charles V of Spain signed the Charter which vested the Order with the "feudal perpetuity" of the Maltese islands and Tripoli. But the Order risked losing the privilege of minting its own coinage. The Viceroy of Sicily informed Grand Master L'Isle Adam that the Emperor would not suffer the Order to mint its own coins on Malta. This was tantamount to a shackling of the Order's independence and was much resented by many knights. This question was settled in the Order's favour through the Pope's intervention.

The Order's coinage reached its apogee on Malta. But by the mid-18th century the Order's currency took a downward turn. A reform of the currency by Grand Master Emmanuel Pinto in 1756 resulted in the issue of new coin types like the gold 10 scudi and the silver 30 tari, which continued to circulate in Malta well after the Order's expulsion from the island by Napoleon in June 1798.

In 1834, after many vicissitudes, the Order established its permanent quarters in Rome. By this time it had abandoned its military function and reverted to its original charitable mission. The constitutional charter of the Order, approved by Pope John XXIII, was promulgated in 1961, and in that year the Order reasserted its minting rights and issued a set of coins which reproduced four designs inspired by the pre-1798 coins minted in Malta.

Today the Order's coinage is principally intended for collectors and is struck in limited numbers. Nevertheless, it remains a potent symbol of the jealously-guarded sovereign status enjoyed by this old yet still vital Order.

This special exhibition will be open to the public at the Central Bank of Malta, Castille Place Valletta on 6 October during the Notte Bianca event. Visitors would also be able to view the other coin exhibits, which form part of the bank's Currency Museum.

During Notte Bianca the bank will be putting up an art exhibition featuring a small number of works by Gabriel Caruana and will be opening the Victor Pasmore Gallery. Numismatic products will also be on sale.