By Richard Ayling - Volunteer Guide

The Legend

If you look up to the southern sky, during the winter, near the constellations of Orion and Taurus there are two bright stars: Castor and Pollux. These two stars are part of the constellation of Gemini.

The constellation is one of the most ancient known star patterns. People have been observing it since earliest human history, and it was first charted by the Greek-Egyptian astronomer Claudius Ptolemy as part of his sky mapping activities. The name "Gemini" is the Latin word meaning "twins," and most star-chart makers depict the stars in this constellation as a pair of twin boys. 

The twins are Castor and Pollux, born by Leda, a queen of Sparta, but respectively fathered by her mortal husband, the King Tyndareus, and the god Zeus (identified by the Romans with Jupiter, King of the Gods).

The Greeks and Romans had many legends about the twins. Some tales are contradictory: this is not an uncommon occurrence in classical mythologies, and did not affect the veneration in which the twins were held.(Ref 1).

All the stories agreed that when Castor was killed, his bother Pollux, who had been offered immortality by Jupiter, insisted on sharing the gift with his brother. But the Fates of the underworld still needed to be appeased, so it was decreed that the twins had to spend the same time above ground as below. For northern hemisphere viewers, the Gemini are a winter star pattern and are not visible in the summer, so the division of their time may be a reference to the constellation’s visibility.

Veneration in Rome

The Greek twins were incorporated into Roman religion relatively early in the Republic’s history.  At the Battle of Lake Regillus , fought sometime between 499 and 489 BCE, the Latin League army, led by Tarquinius the Superbus, the last king of Rome, was defeated by the army of the new Roman Republic. It was claimed by the Romans that Castor and Pollux appeared as horsemen to fight on their side and assured the victory that secured the new regime.

According to the legend, the twins then appeared in the forum to announce the victory before the Romans’ own messengers arrived. This legend continued as Castor and Pollux are said to have reappeared in the Forum to announce victories at other crucial moments in Roman history - after the great battles of Pydna (168 BCE), Vercellae (101 BCE), and Pharsalus (48 BCE).

After their first appearance, the Roman commander, Postumius, decreed that a temple be built to them at the Juturna Spring in the Forum where they watered their horses. The temple became one of the greatest in the Forum, but not just because of the popularity of the twin gods. By the time of the Late Republic, it was a meeting-place for the Senate, with a speakers' platform and voting place outside; it was also the place that magistrates took their oath (Ref 2). It is also suggested that the standardised weights and measures of the Republic were kept in the temple (Ref 3).

In 6 AD Tiberius, stepson and likely successor to the ageing first emperor Augustus, rebuilt the temple on a monumental scale and rededicated it to Pollux and Castor. Note the order of the names, invariably they are referred to as Castor and Pollux. It is possible that Tiberius, by identifying himself and his dead brother, Drusus Germanicus, with the twins (himself with Pollux, as the adopted son of the godlike Emperor, Augustus, and his brother with Castor), was telling Rome that the inheritors of Augustus’ power would be from the ancient and celebrated Claudian family and not the Emperor’s relatively obscure Julian family (Ref 4).  Religion and politics were inextricably intertwined in Rome.

Patrons of the Cavalry and Boxers

Mythologically the twins were matchless horsemen and as such were adopted as the presiding deities of the Roman knights (equites). These were the class of citizens second only to the Senators in wealth and power and traditionally provided the cavalry forces for the Roman Republican army. By the time of the Empire this was not the case, but the Equites were a key element in an Emperor’s ability to rule effectively, providing candidates for many of the key posts in the administration.

Every 15th of July, the rebuilt temple of Pollux and Castor was the focus of a cavalry parade - the transvectio - of 5,000 Equites led by two impersonators of the heroes to commemorate the victory at Regillus. It is possible that this impersonation was the origin of the ornate and elaborate armour, equipment, banners and horse trappings that the cavalry units’ officers and best troopers used when on formal parades (Ref 5).

Pollux and Castor thus became patrons of the hippika gymnasia -exercised on horseback. Such training manouvers took place on a parade ground situated outside some forts and involved the cavalry practicing manoeuvring and the handling of weapons such as javelins and spears. The exercises served several purposes, improving the riders' skills, helping to build unit morale and impressing dignitaries and conquered peoples. At Vindolanda horse fittings are commonly found, and the collection holds no less than seven clearly identifiable fragments of chamfrons, which when complete would have looked like the ceremonial head mask pictured here .

At Vindolanda cavalry units from the Rhineland, Northern France and Spain formed at least part of the garrisons between the 1st and  4th century AD (Ref 6). Amongst the first units stationed at Vindolanda were the VIIII Cohort of Batavians (from the Nijmegen region of the Netherlands). This was an elite cohors milliaria equitata, a unit of almost 1000 troops, of which about 260 were mounted and will have been skilled at horse exercises. It is this unit that produced many of the writing tablets that have made Vindolanda famous. (Ref 7)

In the Vindolanda period 4 (c AD 105-120) a contingent of Vardullian cavalrymen, recruited in northern Spain, were stationed in the fort.  We also know about this cohort from their writing tablets. Finally, from archaeological evidence excavated in the south eastern and south western quadrants of the last stone fort at Vindolanda, we know that at least some cavalry would have been stationed at the fort as part of the IV Cohors’ of Gauls’ tenancy, extending with some pauses between AD 213 and 409.

We can imagine these cavalry units displaying their skills on the forts’ parade grounds, which are believed to be situated to the north of the fort and the road connecting Coria (Corbridge)with Lugovalium (Carlisle) in the west (the Stanegate).  In the Roman Army Museum at Cavoran there is a reconstruction of a Roman auxiliary cavalry man and his mount at full gallop. Not something you would want to try to confront if you were armed only with a spear and shield.

Associations with other cults Going back to the myths of the twins, Castor was an unparalleled boxer too. Boxing was a brutal sport that was practised not only by professional athletes but by troops too. The “gloves” were more akin to hardened leather knuckle dusters, that in professional fights would have had sharp metal edges imbedded in them to maximise the damage to an opponent. In the Vindolanda museum there are the only known examples of these ancient gloves. If you want to know what a Roman boxer looked like look for the decoration situated in the coin section of the museum, that was once the relief on a probable serving bowl.

It is thought that the twins (amongst other deities) were in some way linked with the mystery cult of the god Jupiter -Dolichenus (Ref 8). By the north gate of the Vindolanda a fort, a temple and altar to Jupiter-Dolichenus was discovered in 2009. Were the patrons of the cavalry in some way incorporated into this cult’s rites? We do not know, because the cult’s beliefs, rites and practices were revealed only to the initiated and never recorded (ibid). What we do know, is that the cult of the twins may have been alive and well at Vindolanda in the late 3rd and 4th century. Only a few weeks ago, a relief depicting a naked cavalryman was found in the excavations of the south western quadrant of the last stone fort at Vindolanda. Did the relief depict more ‘traditional’ gods, like Mars or Mercury? Or are we looking at evidence of the worship of one, or both of the twin Gods?

Protectors of Travellers

The twins Castor and Pollux were not only patrons of horsemen and boxers, as well as the harbingers of momentous news. They were the embodiment of brotherly love and from the earliest times were also considered protectors of sailors and all travelers at sea, sharing that dominion with Mercury. St. Elmo’s fire, a luminous plasma created by a strong electric field in the atmosphere when it is near a tall, pointed object such as a mast, was seen by sailors as a good omen and attributed to the twin’s protective aura.

The Gemini were frequently invoked by both men and women for aid in tasks and travel. They were so popular that the early Christian church adopted an ambiguous view of them, rejecting their immortality, but very occasionally incorporating them into Christian iconography (particularly sarcophagi) (Ref 9). However, as time passed, the twin gods were were replaced by St Peter and St Paul, as the protectors of travelers, and by St Comos and St Damian, as healers.

So, when you look up at the winter sky think of the rich story of those bright twin stars.

This blog has been written as part of our Roman Holiday Project.  


  2. Frank, T., & Stevens, G. P. (1925). The First and Second Temples of Castor at Rome. Memoirs of the American Academy in Rome, 5.
  3. Frank, T., & Stevens, G. P. (1925). The First and Second Temples of Castor at Rome. Memoirs of the American Academy in Rome, 5.
  4. Champlin, E. (2011). Tiberius and the Heavenly Twins. In Source: The Journal of Roman Studies (Vol. 101)
  5. Valerie A. Maxfield. (1981). The military decorations of the Roman Army. University of California Press in Berkeley.
  6. Vindolanda: A Roman frontier fort on Hadrian’s wall R Birley Amberley 2009
  7. Garrison Life at Vindolanda: a Band of Brothers. Charleston, S. C: Tempus Publishing; dist. by Arcadia Publishing, Charleston, S. C. 2002.
  9. Couzin, R. (2017). Syncretism and Segregation in Early Christian Art. Studies in Iconography, 38, 18–54.

For information on the constellation of the Gemini go to: