The Knights Templar - real military order
They formed shortly after the Crusades began in around 1120 and were headed by a French knight called Hugues de Payens. Their true name is Knights of Christ in the Temple of Solomon in Jerusalem. They had indeed established themselves in the Temple of Solomon but became known as the Poor Knights of the Temple, or The Knights Templar.
There is tell that the order became guardians of the Holy Grail after they discovered it hidden under the floor of the Temple of Solomon. The Grail was reportedly secreted there sometime during the Herodian Dynasty after the death of Christ. The trouble is that by the time The Knights Templar were in the temple, they would have had to dig down about 47 metres to reach the level of the Herodian Dynasty. There is no existing evidence of a huge dig like this, which makes it seem unlikely.
In time, the Templars garnered favour with noble families who travelled under their protection. They began attracting recruits from the ranks of these families as well. They received donations of vast material wealth and succeeded in setting up the first system of international banking.
Now wealthy and enormously well connected, the Templars were an obvious target for those who believed they could better use their riches. Philip IV of France condemned them as heretics and organised a brilliantly orchestrated coup. On 13 October 1307, the Templars were individually hunted down and tortured or destroyed for their crime. The order, which had been officially recognised by the Vatican, was denounced by Pope Clement V at the same time. It's not known if any knights survived or whether the Templar still exists.