Rabbinic Judaism and orthodox Christianity emerged from the same culture, and for a few centuries their houses of worship were strikingly similar in design and decoration. The iconography was mostly symbolic, though with occasional narrative scenes. Jews and Christians even tended to favor the same symbols (fish, peacock, dove) and the same biblical narratives (Abraham and Isaac, Noah and the Ark). The two groups often lived in close proximity, and influence ran both ways across the street. It’s only in later centuries that synagogues tended to be strictly and almost universally aniconic (forbidding images).
With all that in mind, you might want to visit this excavation of a synagogue in Albania, from the pages of Archaeology magazine:
Colorful mosaic pavements and the fifth- or sixth-century A.D. synagogue that housed them were unearthed in the Albanian coastal town of Saranda, opposite the Greek island of Corfu. It is the first time such remains have been found from this region and time period.
Albanian archaeologists first discovered remnants of a house of worship 20 years ago during an initial excavation of the site, when Communist prohibition of religion made a more thorough survey difficult. Because the structure had undergone multiple uses throughout the centuries–most recently as a Christian church–the synagogue remained well hidden for years. When further excavations uncovered evidence of the structure’s Jewish past, the Archaeology Institute of the Albanian Academy of Sciences teamed up in 2003 with archaeologists from the Hebrew University Institute of Archaeology for a joint excavation.
The first mosaic pavement depicts items associated with Jewish holidays: a menorah, a citron tree, and a ram’s horn. The other, located in the basilica of the synagogue, includes trees, animals, and the facade of a structure that may be a Torah shrine. Future excavations will venture beneath adjacent streets and buildings, where parts of the synagogue remain.
You’ll find a lovely (copyrighted) selection of photos from Saranda here, with close-ups of some of the mosaics.
For more on Jewish-Christian mutual influence in antiquity, see Rodney Stark’s The Rise of Christianity: How the Obscure Jesus Movement Became the Dominant Religious Force in the Western World in a Few Centuries.