"There is not a word about synagogues in the Old Testament, not even in the latest-written chapters; but as soon as we read on into the four Gospels we find them everywhere, a synagogue to practically every occurpied locality of the Land; and when we read on into the Acts of the Apostles we find them similarly established everywhere among the many Jewish communities throughout the Roman empire." 
(Explore the Book by J. Sidlow Baxter)