Mithras: A Secret Cult at the Fringes of the Roman Empire

In the far north of the Roman Empire, where the climate was harsh and survival uncertain, a group of soldiers lit lamps in the darkness of an underground temple. Before them, the face of a god carved in stone gazed back.

Nearly 2,000 years later, that altar reappeared in Scotland, changing what we know about life on the frontier of the Roman Empire. In 2010, archaeologists in Inveresk—surveying the site for a cricket pavilion—made an unexpected discovery. They unearthed two altars that date back to around A.D. 140, when the territory was reoccupied under Emperor Antoninus Pius. One altar was dedicated to the sun god Sol, a symbol of light, order and cosmic power; the other was consecrated to Mithras, a deity associated with salvation and protection. Notably, this is the first evidence of a cult of Mithras worship in Scotland, the northernmost point of Rome's expanse.

“On the northernmost frontier, you need to have the gods on your side, because it’s an uncertain time and an uncertain area. And for some soldiers, Mithras was the god they chose,” explains Fraser Hunter, senior curator of prehistory and Roman archaeology at the National Museum of Scotland. “It makes us rethink what we thought we knew about Romans in Scotland.”

Unlike other Roman gods, Mithras' cult—known as Mithraism—left no sacred texts or written accounts. Everything we know comes from temples and reliefs found across ruins.

Mithras originated as an ancient Indo-Iranian deity (Mithra) associated with pacts, loyalty and order, later adopted and transformed by the Romans. He was often depicted as a young man wearing a Phrygian cap (a soft, conical cap associated with the ancient Near East sacrificing a bull inside a cave. Known as the tauroctony, this scene does not depict an ordinary sacrifice. Rather, it's a broader representation of renewal and cosmic balance, in which the animal’s death gives rise to new life. For initiates of Mithraism, it symbolized the tension between opposing forces—light and darkness, life and death—which the god helped to harmonize.

The cult of Mithras was exclusively male and became especially popular among soldiers. Practices were organized around initiation rituals at different levels. Its temples, known as mithraea, were often located underground, reinforcing the secretive and initiatory nature of the cult.

Another recurring image shows Mithras emerging from a rock, fully formed, a motif known as the petra genetrix. This unusual birth, which bypasses the need for a mother, has often been linked to the cult’s exclusively male membership.

On the fringes of the Roman Empire, where soldiers needed to believe they were not alone, Mithras likely offered more than divine protection. “He offered hope for the future,” says Hunter. “If you’re a soldier whose fate is literally in the hands of the gods, having a god like Mithras on your side must have been incredibly powerful.”

The altars found at Inveresk introduce another unexpected element to Mithraism. Although one altar is clearly dedicated to Mithras, its reliefs do not entirely follow the typical iconography of the cult. Instead of the classic tauroctony scenes, it features a griffin—a mythical half-lion, half-eagle creature of eastern origin—and a lyre with a plectrum (a pick). These images are traditionally associated with the god Apollo, another deity linked to light. The altar also depicts two ravens, animals which commonly appear in Mithraic iconography. The combination suggests that in an early phase of Mithraism, the deity could have been associated with—or even assimilated to—other gods.

Additionally, the other altar dedicated to Sol features a striking visual effect. Illuminated from behind, in the dimness of the temple, it would have made the sun god's eyes, mouth and the rays of his crown appear to shine. The scene is completed by representations of the four seasons—female figures symbolizing the passage of time—another recurring theme in the symbolic universe of Mithraism.

Both altars were consecrated by a legionary centurion (a professional officer in the Roman army) whose name appears in abbreviated form as G CAS FLA. This most likely refers to Gaius Cassius Flavianus, who commanded the troops in the area.

The discovery of the altars also helps to dismantle a persistent misconception: that the Roman Empire never advanced beyond Hadrian’s Wall—fortifications built during the conquest of Britain in the second century. Although the wall is often considered Rome’s northernmost limit, the Empire in fact extended its presence several times farther north into central Scotland.

During the reign of Antoninus Pius, another defensive line—the Antonine Wall—was constructed between the estuaries of the Forth and the Clyde. It was accompanied by forts and settlements such as Inveresk, which became an important military and civilian center.

After their discovery, the altars—made of sandstone and fragmented after nearly 1,800 years underground—were dismantled, treated with specialized chemicals and reassembled by conservators at the National Museum of Scotland, where they will be on display for the first time in November 2026. Buried face down when the temple was abandoned, these artifacts were protected from the elements and the reliefs have retained exceptional clarity, including traces of pigment.

The altars reveal not only religious practices but also daily life in the wider Empire. “This is one of those discoveries that changes the way we understand the Roman frontier,” says Hunter.