The focus for this study is the collection of mosaic-floors that adorn the entrances, fauces, to atrium-houses around Pompeii. The aim is to further our understanding of the Roman view of transitional spaces, in this case the private house-entrance between the inside and the outside world. Contemporary approaches to Pompeian studies regard space and décor as closely intertwined components, which suggests that the designs for an entrance-decoration were intended to convey an appropriate message. Ever since the early excavations of Pompeii, especially the figurative fauces-mosaics have been recognised, leaving the non-figurative mosaics less emphasised (and still so today), although outnumbering the others. In order to provide a more holistic and nuanced picture, the present study is based on several contextualising steps, which take into account the (rather low) number of fauces-mosaics (in 29 houses); the houses’ topographical distribution within the city; their sizes and general interior decoration-level; the fauces-passages’ spatial design and layout; the temporal framework of the fauces-mosaics (ranging between c. 100 B.C. to A.D. 79) and the iconographical subject-matter of the mosaics. The results of the study show that certain clusters can be discerned, particularly so of a “fashion” for fauces-mosaics in the large terrace-houses during the late Republic. Moreover, many of the mosaic-motifs alluded to mundane matters instead of religious, and the general attitude to the outside world was one centred around a positive and greeting communication. By laying a fauces-mosaic, a house-owner intentionally conveyed that his or her house was worthy of attention. Nevertheless, it is also clear that a superstitious perception of the entrance acknowledged its need of protection. In some cases, defending symbols on the mosaics do point to such a paradoxical awareness of the owners.