Q: Christians go to church, Jews go to synagogue. Muslims go to mosque. Where can Noachides come together?
A: Noahides can come to synagogues, but they should announce to the Shamash that they cannot participate as a part of the Minyan (=the minimum of ten male adult jews required for the public prayer) or in the public reading of the Torah. In ancient times, there was a special area in the synagogue for Noahides, who were known as "Yirei Hashem" (G-d fearing people). When the phenomem of Noahism will be more prominent than now, it will be possible to re-create this institution. Another possibility, which is used in some places in the world, is to establish Noahide meeting places ("synagogues") for studying and praying together, or for social gatherings.