A short drive west from Trieste and just above the town of Duino, in the Italian region of Friuli-Venezia Giulia, there is a Roman Mithraeum that dates to the first century B.C.

A Mithraeum is a temple sacred to those who worshipped the god Mithras and followers of the Mithraic mysteries. Most Mithraeae are found in what was the Ancient Roman Empire. Although Mithras derives from the Zoroastrian divinity Mithra, the Roman mystery religion has its own separate imagery and set. This ancient religion was common among the army, which is likely how it ended up in a seemingly random spot on the karstic hills of the Trieste Gulf.

A Roman detachment established the ancient city of Tergeste (modern-day Trieste), which is likely how the Mithraic religon was brought here. The location was strategic, as it sat just above the mouth of the Timavo river, overlooking the surrounding landscape with clear views to the east, south, and west. It was also located near the main Roman road commonly known as the Via Iulia Augusta.

The small natural cave roughly faces southwest. The "benches" originally served as an altar. There are two casts of the two original carvings (the original ones are at the museum in Trieste) representing Mythras with the bull, its typical depiction. The main carving, the one at the center of the Temple, represents the god slaying the bull.

To the right, you can see the bottom part of the well (which you pass when you arrive) that was likely used as drainage for the blood from the ritual animal sacrifice.