Aside from their famous members throughout history — from George Washington and Benjamin Franklin to Thurgood Marshall and Harry Houdini — the Freemasons are known as one of the most secretive organizations in the world. With roots in religious faith and a self-improvement mission that has evolved over centuries, they conduct much of their business behind closed doors in ways known only to members.

But the La Jolla branch opened its lodge to non-members Dec. 13 for a dinner to help celebrate its 100th anniversary.

The history of Freemasons — now considered a fraternity-type association “dedicated to fostering and promoting every moral and social virtue in men” — goes back to the construction of the biblical King Solomon’s Temple in Jerusalem in the 10th century BCE.

“That building marked the first time there were stonemasons that [created] industry,” said Freemason Johnny Law, and rituals were built around the traditions between stonemasons in the earliest guilds. “Since they couldn’t read or write, they had to come up with secret handshakes to indicate their … level or skill set,” Law said. “It was a way to recognize one another.”