One of the four palace vaults uncovered in Caesarea Maritima is of particular interest due to its use as a Mithraeum, a place dedicated to the practice of Mithraism. Mithraism was a mystery religion commonly practiced throughout much of the Roman Empire during the first centuries of the Common Era. Everett Ferguson tells us:
After the late first century A.D. archaeological evidence for Mithraism begins to increase; at the end of the second century the emperor Commodus was initiated; it was strongest during the third century, when it was a significant element in Julian’s attempt to reestablish paganism. The main strength of Mithraism, according to the surviving monuments and sanctuaries, was among Roman soldiers and administrative officials along the frontier, from Hadrian’s wall in Britain to Dura Europus on the Euphrates. Only men were admitted to the mysteries, and Mithras as a warrior and guardian of oaths appealed to manly pride. Mithraism also flourished at seaports … and it was well represented in and around Rome, thus indicating its appeal to merchants and city-dwellers as well as soldiers. … It seems never to have had much of a hold in Palestine, where to date only one Mithraeum has been discovered. At Caeasarea one of the warehouses dated from the late first to the third century was used as a Mithraeum in the third century. (Backgrounds of Early Christianity, 3rd edition; pp. 290-291)
A historical marker in front of the Mithraeum in Caesarea Maritima reads:
In the early 2nd c. A.D., one vault was converted into a “Mithraeum.” The contrast between the dark vault and the shaft of sunlight reaching directly the altar from the opening made in the ceiling, played a role in the cult of Mithras, known as the “Unconquered Sun.