The cross is one of humanity’s more ancient and ubiquitous symbols. An early interpretation was as a representation of the intersection between the divine (the vertical line) and the earthly (the horizontal line). In modern times this has been trivialized in our use of the cross on road signs to signify an intersection of roads ahead.
The cross has also represented the division of the world into four elements, the four cardinal points on the compass, man, and of course, the symbolism of the crucifiction associated with Christian religions around the world. While this last may be the most familiar (along with the common road sign), it is worth imagining the many other possible meanings when confronted with the image of a cross in unexpected places.