Mithraeum of the Seven Spheres
Step down into the Mithraeum of the Seven Spheres and the first thing you notice is the floor. Seven black mosaic arches run the length of the narrow room — 11 metres long, barely four wide — each one representing a heavenly sphere governed by a planet and its corresponding grade of initiation. The arches gave the shrine its modern name, and they're the reason scholars still argue over what exactly happened here.
This is one of the best-preserved of the eighteen Mithraic shrines scattered across Ostia Antica. At the far end, a marble relief of Mithras killing the bull is set into the back wall — the original removed, a plaster cast left in its place. Side benches once seated around thirty-two men. Two small travertine altars sit embedded in the bench corners.
💛 What travellers fall for
People who come back tend to linger on the floor mosaics longer than they planned. Bring a phone torch — the light inside is low and the black-and-white geometry rewards a close look. The plaster cast of the Mithras relief reads better than you'd expect once your eyes adjust.
The story behind Mithraeum of the Seven Spheres
The shrine was first excavated between 1802 and 1804 by Petrini. Its brick construction and mosaics were later dated by Giovanni Becatti to the Antonine period, though some scholars place it in the third century. The astronomical floor mosaics may encode a specific celestial event — a Saturn-Jupiter conjunction thought to correspond to the spring equinox of 172 or 173 AD.
Three figures left their names on the record: A. Decimius Decimianus restored the shrine and its vestibule; L. Tullius Agatho dedicated an altar to Sol Mithras; and M. Aemilius Epaphroditus served as pater and sacerdos — father and priest — the highest grade within the cult's seven-tier hierarchy that the floor itself was designed to represent.
Good to know
Take Metro B to Piramide, then the Roma Lido commuter train (€1.50, about 30 minutes) to Ostia Antica station — ten minutes on foot from there to the site entrance. Tickets are €14; the first Sunday of each month is free. Closed Mondays, 25 December and 1 January. Budget at least a half day for the wider site.
April through October gives you the most workable conditions — warm and generally dry, with July offering over eleven hours of daylight. August peaks around 29°C with little shade on site, so carry water and a hat. November through March can be cool and wet, with very short days in December.
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What travellers say about Mithraeum of the Seven Spheres
beautiful mosaic left gor u to discover, not crowded at all
Yes, another thermal complex, with some astonishing underground surprises, get there and find what I am talking about...
I was amazed by the tauroctony statue on display in the Ostia Museum (it's enormous, the only statue of a Mithraeum I've ever seen; until now, I'd only encountered paintings, bas-reliefs, and high-reliefs, never a sculptural complex). I immediately set out to find the site, and thanks to Maps and a few directions, I was surprised: from the bookshop and bar area, a small gravel road will lead you to the site, which includes the baths at the top. A small staircase leads down to a space that—originally built under Hadrian—was later used for the cult of Mithras, after some modifications were made, such as the addition of two side seats for spectators to watch the ceremonies. The most exciting thing, thanks to the presence of a plaster cast, is the statue of the deity (in Greek robes but without the Phrygian cap) at the very back of the room and illuminated by a skylight above. Upon entering, despite the dark underground location, you're immediately greeted by the image of the bull being killed, which makes everything very evocative, even more so considering that until recently it was inaccessible and often filled with water. Thanks to the inscription on the bull (see the original inside the museum, in the cult room), we also know who created the sculpture. It's definitely worth a visit, and if you're near the museum or a restaurant, consider stopping by. Need some useful info? Like and check out my other reviews of Ostia, Rome, and more.
Visiting this site is evocative and fascinating. It's not the easiest thing to find, but you can get there using Google Maps. The statue of Mithras slaying the bull is illuminated by a skylight and is a cast. The original is in the museum.
If you visit Ancient Ostia you absolutely must see this very suggestive structure too!!
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