there are lots of speculations and assertions (conspiracy theories?) out there about the Knights Templar digging under the Temple Mount in Jerusalem looking for religious relics, specifically the holy Grail.
Did the Knights Templar believe the holy Grail was an actual physical object that could be found? Did they ever look for it? did the Knights Templar conduct any kind of archaeological digs under the Temple Mount?
Perhaps there's someone who knows exactly what documents of the Templars survived their destruction , by Phillip the Fair and others, in 1307. But as simply a matter of medieval Christian practice, EVERYONE would be looking for holy relics, trading them, selling them, buying them, stealing them from the neighboring village, to put into their own church, so pilgrims would come. Bits and pieces of saints and martyrs and fragments of their clothes and even the dirt they were buried in was thought to be able to do all sorts of handy things, especially cure sickness. And they were often "revealed" when there was a need- ( like the discovery of the Holy Lance that pierced Christ's side, that Peter Bartholomew found during the First Crusade right when it was useful). So, it's almost impossible for anyone to claim that, as a general rule, the Templars would NOT be looking for relics, of any kind.