One of the most important symbols associated with the Camino is the Tau Cross, which we can see, for example, in the Glory’s Portico at the Santiago Cathedral, where the apostle is represented with a staff shaped in this way.
The cross has a long tradition behind it, starting in the egyptian and greek cultures. In the Christian era, the cross first became the symbol of St. Anthony of Egypt, and then of the congregation that bore his name, the Hospital Brothers of St. Anthony, who founded several hospices along the Camino (for example, at Castrojeriz). Later, St. Francis of Assisi also adpoted the cross as his coat of arms.
Besides all of that, the Tau Cross is also associated with a medieval navigation instrument. Jacob’s Staff, which has a shape similar to that of the cross, was used to measure the height of the stars over the horizon.