The ancient practice of decorating sacred buildings differs greatly from that in previous cultures and contemporary or later ones, where sanctuaries are recognisable from exterior and interior alike as such. The architecture, form, building elements and decoration (e.g. paintings) betray at first glance where the visitor is -in an Egyptian temple, in a Catholic cathedral, in a Protestant church, in a mosque or a Buddhist temple. An image of the god or saint in the façade informs the viewer about the god or saint venerated here. In the case of an icon-forbidding religion, there may be a token like the Holy Cross or the Star of David or the presence of an architectural feature like a minaret. The interior of the shrines also plays a significant role in helping to identify the purpose and religious affiliation of the building from the moment worshippers enter and address the gods and saints within the building. We recognise the mihrab in the mosque, the altars in most other religious buildings, the statues, icons and mural decorations displaying the venerated persons and their entourage. In the latter case, the iconographical programmes or schemes may be fixed so that the definition of the specific figure worshipped is not immediately clear, but an attentive look will soon reveal who is presiding there.

When we turn to Antiquity, we see that the exterior of ‘classical’ Greek and Roman temple is recognisable immediately thanks to typical features like the stylobate, peripteros, podium and façade. This does not hold true for many other shrines that both architecturally and in the sense of decoration often do not differ notably from houses.

Decorations in painted form within religious complexes of the ancient world have not yet been studied as a genre – if this word can serve to indicate the specific case – and I hope that this book will fill a gap. Current research on exterior decorations of religious buildings in general shows a major interest in the sculpted decorations, which became fashionable in the Greek and Etruscan worlds in the early sixth century BC and in Rome, especially from the late Republican era onwards, than in the paintings and mosaics on walls and floors. Such adornments and revetments -preferably in marble, but even those in limestone and terracotta -and, especially, sculptural decorations (including those in terracotta) have a stronger visual appeal to the person approaching the sacred building.