What Is The Symbol That Always Seen Around The A Synagogue?

I'm not even sure what you mean but I found this interesting tidbit at  www.greatsynagogue.org />There are no images, icons or statues, and no representation of God
or the human form in the synagogue. Occasionally there will be decorations based
on Jewish religious motifs (the Ten Commandments, menorah, etc.). Lions may
possibly figure on the Ark curtain or Torah ornaments, since the lion is the badge
of the tribe of Judah, from which come the names Jews and Judaism. God has no
physical form. Jews do not accord Divine status to any human being. Religious
motifs intensify the congregation's loyalty to the tradition. Synagogues often have
12 windows representing the 12 tribes of ancient Israel. The windows of the
synagogue symbolically allow the light of faith to shine on the world outside.

It's the Star of David