There is evidence that each of the Seven Churches address in Rev. 2-3 were in cities which included Jewish populations. The synagogue at Sardis has been excavated. Fatih Cimok, in A Guide to the Seven Churches, writes:
The synagogue in Sardis is the largest of its type known to date. Excavations show that the building was originally a civic basilica which was built between the main street and the gymnasium and converted into a synagogue sometime between 150-350 C.E. Its unusually large dimensions and rich decoration, as well as the titles of the Jews mentioned in the inscriptions here, show the high status that the Jewish community in Sardis held.
In its final form the synagogue which is thought to date from about 320-40 CE consisted of a colonnaded entrance court and a long assembly hall (p.81).
Pictured below is the Sardis synagogue:
Click on photo for larger view. In our photo you can see the forecourt fountain. In the distance you can see the main hall with table. Cimok gives the seating capacity of the main hall as one thousand occupants.
More to come.