"This is a place free of fear!"
This Greek text was placed in front of the entrance of one of the tombs on the ancient Roman burial place. The text forms part of a mosaic on which we can see two sailing vessels entering the harbour of Portus.
For the "inhabitants" of this necropolis, the text had a double meaning.
The vessels were brought into a place outside the reach of the dangerous sea and, similarly, the deceased had, by taking his last boat trip over the river Styx, changed his worldly vale of tears into the eternal peace of the underworld.
For me, as the author of this part of the Ostia website, there is a third sense.