What were the Knights templars main duties?

There is much mystery shrouded around the Templars. They are most known to have been started to act as bodyguards for the christian pilgrims, coming to visit "the holy places" after Jerusalem was captured in the first crusade. Protecting them from The places in Outremer, where bandits would sometimes slaughter pilgrims by the hundreds. But, many people believe, that since the order had gained so much power, power competable with that of the Roman Catholic church, there had to be much more to them. Some believe them to have owned many religious relics, to be the keepers, and protecters of the Holy Grail. Also, they were known freemasons, and history's first bankers.