Both sides of this coin show the sea-god Poseidon in a striding pose, with his trident held above his head – a pose characteristic of late Archaic art. The use of Poseidon as a coin design made it easy for people who couldn't read to identify the city of Poseidonia as its mint. However, the coin stands out because of its remarkable design: while the god on the front of the coin is in relief, the reverse is indented, carefully matching the front figure in the negative. We do not know why Poseidonia and other cities in southern Italy produced coins using this unusual technique.

Money in China developed initially in the shape of real metal tools which would have held value. From 1500 to 200 BC, cowrie shells as well as objects in the shape of spades, sickles (knives) and hoes were used as currency, suggesting a link between such tools used in barter and stylised objects of similar shapes used as money. This example is a 2-kin 'spade' coin from the Zhou dynasty period. It is inscribed with the name of the city of An-i, where it was made, along with its weight and the word ‘current’.

The front of this coin shows a posthumous portrait of Alexander the Great (336–323 BC) produced by Lysimachus, one of Alexander’s successors, around 280 BC. Alexander is wearing a diadem, the headband that became a symbol of kingship. He is also shown with the ram’s horns. They allude to Alexander’s visit to the oracle at Siwa in Egypt in 331 BC, where he was proclaimed to be the son of the god Zeus Ammon. Lysimachus invoked the powerful image of Alexander on his coins to bolster his own legitimacy. Not on display.

Coins can sometimes be the only surviving sources of history. This little coin, bearing the name of the king under whom it was issued, Agathocles, was made in Gandhara, an ancient region in modern-day Pakistan, which was considered a crossroads between Central Asia, Ancient India, and the Middle East. The coin is bilingual, with the king’s name written in Greek on one side and in an Indian script, Brahmi, on the other. The images, too, show different cultural influences, with a panther (an animal associated with the Greek god Dionysus) and a female figure, perhaps to be identified as an Indian deity, holding a lotus flower.

This silver tetradrachm of Azilises, an Indo-Scythian king who ruled in Afghanistan–Pakistan, depicts ‘Abhisheka Lakshmi’, the Indian goddess of fertility and plenitude. She stands facing forwards, on a lotus with two more long-stemmed lotuses carrying elephants. The depiction has fertility connotations with the goddess representing the Earth and the elephants as rain-bearing Monsoon clouds. The Indo-Scythians were nomads from Central Asia. Like Agathocles before them, they chose a range of gods and goddesses from different pantheons to be depicted on their coin, perhaps to appeal to audiences from different cultural backgrounds.

Julius Caesar is a well-known figure in Roman history. Conqueror of the Gauls, he accumulated so many powers that many feared that the Roman Republic was at risk. During the year 44 BC, Caesar's portrait appeared on coins (above, top). This was considered too much: no Roman had ever done this before him, and only the (Greek) kings who succeeded Alexander the Great were doing so! On 15 March 44 BC — the Ides of March — Brutus and his allies assassinated Caesar, triggering the start of a long conflict that eventually saw the end of the Roman Republic and the beginning of the Roman Empire. The second EID MAR silver coin (above, below left & right) was made by Brutus to celebrate his assassination of Julius Caesar in 44 BC. Ironically, his portrait appears on the coin, as only Caesar had done before him.

This bronze coin was issued by the city of Stratonicea (now in Western Turkey) and served as local small change. Originally, its front showed the facing portraits of the brothers and Roman co-emperors Caracalla and Geta. Caracalla had his brother murdered in AD 211 and condemned his memory. Consequently, Geta’s portrait was erased (it would have been shown on the right of the above), while that of Caracalla was left intact.

The 3rd century AD was a period of crisis and transition for the Roman Empire. After the long and relatively peaceful dynasties of the 2nd century, numerous emperors followed one after another, often in quick succession. As a result, the coherence of the Empire was weakened. In Britain, Gaul and Spain, a general named Postumus (AD 260–9) was celebrated as Roman Emperor, although he failed to be recognised as such by the central administration of Rome. This bronze medallion shows Postumus with the god Hercules — famous for his strength and adventures — as his ally.

This gold dinar dates to the era of Chandra Gupta II in the Gupta dynasty. It shows the king hunting a lion by shooting an arrow at his head. Gupta gold coins are often considered to be the height of ancient Indian coin design. They depict an image of the king, usually with a representation of Lakshmi, the goddess of fortune and plenitude on the reverse. Here her right hand is shown making a gesture of benevolence, scattering coins.

The Roman Empire came to an end in western Europe in the 5th century, but survived for another 1,000 years in the eastern Mediterranean, in the form of what we now call the Byzantine Empire. This was a large and populous state, ruled centrally by a Christian emperor from Constantinople (now Istanbul). Its political and economic might was symbolised by the imperial gold currency. This coin is both overtly Christian and imperial. It was the first to feature a representation of Christ on the front. The decision to re-design the coinage in this way must be understood in the context of the rise of a rival religious empire, the Islamic Caliphate.

In the medieval Christian West, authority was often delegated. Monasteries and nunneries were important spiritual and economic centres, and the heads of house also fulfilled political functions, such as overseeing the issuing of coinage. Quedlinburg Abbey in north-central Germany was a royal endowment and answered directly to the popes in Rome. Pennies such as this coin were typical for this part of Germany in the 12th century. In an attempt to supply an ever-increasing population with adequate numbers of coins, individual coins were kept excessively light and thin. This allowed for only one side of the coin to be stamped with a die.

This three pound gold coin was made in Edinburgh in 1555. The front shows a portrait of Mary, Queen of Scots while the other side shows a crowned shield of the arms of Scotland. When the coin was produced Mary was only 13, having acceded to the throne when she was just six days old, and was living in France where, three years later she was to marry the heir to the French crown before returning to Scotland. The image of Mary on the coin is very similar to what appears in contemporary portraits, in which she wears a similar necklace and hair decoration.

During the English Civil War, Charles I moved his court to Oxford between 1642 and 1646. Cut off from the Royal Mint in London, Charles needed a way of paying for his war effort. Partially using melted down silver from the University’s colleges, as well as foreign currency, the Oxford mint produced a large number of coins. The front of this ‘Oxford crown’ shows the king on horseback with the skyline of the city of Oxford below.

The Nigerian manilla shown here with a horseshoe shape and flattened broad terminals, was known as the ‘Mkporo’ or ‘Okpoko’ manilla. The word ‘okpoko’ is synonymous with ‘money’ or ‘brass’ in several West African languages like Calabar, Efik and Ibibio. Manillas of copper and brass were the first true general-purpose currency known in West Africa, used for ordinary market purchases, bride price, payment of fines, compensation of diviners, and as burial money for the after life. They also become a principle currency in the West African slave trade. Millions, like this piece, were manufactured in Birmingham for export to West Africa. Pictures of manillas also featured on five-shilling banknotes of Biafra, the breakaway South Nigerian Republic, issued in 1968.

This large gold coin was minted in Tehran in the early 19th century, in the Qajar period, during the reign of Fateh Ali Shah. It's anonymous, but bears the royal emblem of the Qajar dynasty – a rising sun depicted against a lion. The inscriptions invoke the prophet Muhammad and the Imam ‘Ali, regarded as the highest authorities of Shi’i Islam. The coin was among many which were stored in the treasury and used by the Shah of Iran to pay an indemnity to the Russian Czar after his defeat at the hands of Russia in 182. Heavyweight, multi-denominational coins like this were often produced as a store of wealth to be kept in the royal treasury.

Received in change by an Ashmolean curator in New York in 1998 and kindly donated to the Museum, this US $50 banknote illustrates the way in which monetary objects can be used in unexpected ways after their production. Although we do not know the full context in which the words ‘Lesbian Money’ were stamped on the note, there is a long tradition of using the defacement of currency as a way to spread a particular message, in this case highlighting the buying power, and, indeed, the existence, of the lesbian community.