Traditionally each town of ten or more Jewish men could establish a synagogue. The building served as a religious school for the boys during the day (conducted by the scribes) and on the Sabbath as a gathering place to worship and to receive teaching – during which the men and women sat separately.
The synagogue leader readily invited visiting rabbis to teach and speak as happened with Jesus, Barnabas and Paul (Mt 4:23; Lk 4:16-32; Act 13:14,15, 17:1,2).
The Temple in Jerusalem contained the Ark of the Covenant, and was the only place where sacrifices could be offered. It was highly regarded and respected by most Jews, and all the men were required to attend three annual feasts there. However, it wasn’t practical or even possible for many Jews to travel long distances (from throughout Israel) to it each week, especially considering the Sabbath day journey restriction of about a kilometre (Act 1:12). Jerusalem had numerous synagogues.