This exercise appears at first sight to apply to the countryside, but there is no reason why it should not be used in an urban setting. C S Lewis once observed that 'next to the Blessed Sacrament itself your neighbour is the most holy thing which will ever present itself to the senses' and in the city there will be many signs, if we are sufficiently aware, of men and women having been open to the Spirit of God. There are also, even in the city, surprisingly numerous evidences of the natural world burgeoning amidst the concrete, for those who have eyes to see.
For use in a group one could well begin indoors - or in a garden or other outdoor space - with a few centring down exercises, and then send members off with a request to re-assemble in an agreed length of time (perhaps not more than half an hour if you don't know the group very well). They could either go singly, or as an 'Emmaus walk' in twos, but with the suggestion that the walk be done in silence. If in twos, the story of the Road to Emmaus could be read aloud in the group before setting out.
On re-assembling, group members will wish to share their reflections, their awareness, and in particular any meaningful items they have brought back with them.
A period of prayer could end the session with the freedom of a choice of silence or open verbal prayer.