Most people’s knowledge of The Knights Templar likely came from the book or film version of Dan Brown’s “The Da Vinci Code,” but there’s so much more to this order than that. The Knights Templar is an ancient, secretive order that is said to guard the secret of the Holy Grail still to this day. If you’re interested in controversial history, your trip to Portugal wouldn’t be complete without visiting Tomar where the Knights Templar Castle remains.