If memory serves, many Cathedrals and other churches in Europe had labyrinths marked out - sometimes on the floor inside, sometimes outside in the churchyard - in the Middle Ages - and people used them in prayer.
The origin was that it was meant to symbolically take the place of a pilgrimage to Jerusalem for those who had neither the time or money to go on a real journey to the Holy Land.
Having said that, perhaps find out more about what they will actually be doing while there, and if there are any particular prayers they will be using and so on.
