The Knights Templar, also known as the Poor Fellow-Soldiers of Christ and of the Temple of Solomon, were an order of Christian knights that was formed in approximately 1119 A.D., following the First Crusade. The stated responsibility of the Knights Templar was to protect Christian pilgrims who were traveling to Jerusalem. The Knights Templar were given the Temple Mount in Jerusalem as their headquarters, and there are many legends of the Templars excavating the many tunnels beneath the Temple Mount in search of biblical treasures and artifacts.
Primarily due to a financial dispute with King Philip IV of France, the Knights Templar were ordered to be disbanded by Pope Clement V. Many of the Knights Templar were arrested, tortured until they confessed to unimaginable crimes, and then burned at the stake as heretics. Some of the Knights Templar escaped the persecution and went into hiding. There are various traditions as to what happened to the surviving Knights Templar, with the most likely legend being that they eventually formed what is now known as the Freemasons.
The recent books, Holy Blood, Holy Grail and The Da Vinci Code include the Knights Templar in their conspiracy theories. The legend says that the Knights Templar found evidence that Jesus was married to Mary Magdalene, and they blackmailed the Roman Catholic Church, leading to the legendary wealth of the Knights Templar. Eventually, though, the Roman Catholic Church was able to orchestrate the heresy charges against the Knights Templar, leading to their disbanding and deaths. Similar to the other conspiracy theories in Holy Blood, Holy Grail and The Da Vinci Code, these theories are completely lacking in historical merit.