Sanctuary of Isis and Magna Mater, Roman sanctuary remains in the Römerpassage, Mainz, Germany

The Sanctuary of Isis and Magna Mater survives as low walls of rough-cut grey stone blocks forming rectangular foundations in the basement of the Römerpassage. Shallow square and rectangular recesses sit lower than the surrounding masonry, and smooth dark paths run between the remains. Tall dark pillars and thinner pale panels stand among the walls under a dark ceiling set with small lights, with a low metal railing and illuminated display cases at the far edge.

This sanctuary was built during the Flavian period in the late 1st century and served as a religious center for generations. It gradually fell out of use around the 3rd century as religious practices in the region shifted and changed.

Inscriptions name Isis Panthea and Regina alongside Magna Mater, and a building inscription records the treasury administrator Primigenius, subordinate to a procurator of Vespasian, as builder. The addressee there is given only as [Mater] deum, probably Cybele. In the basement display, a staged ritual scene and an audio sequence with a fictional contemporary witness present cult practice in first-century Mogontiacum.

The site is easily accessible by public transportation and sits directly beneath the modern city center. Access is provided through a covered passage that accommodates visitors with mobility challenges.

The exhibition room is kept dark, and small lamps set into the ceiling reproduce the night sky of 21 December 69 CE, the year Vespasian's reign began. A glass walkway runs around the exposed walls, and a staged ritual scene with audio stations shows how the cult was practised.