John is known as the spiritual Gospel because, among other reasons, it has extended metaphorical discourses, such as the bread of heaven (6:25-59), and a long, one-on-one dialogue with the religious leader Nicodemus about deep truths (3:1-15).
Until recently, much scholarship did not take seriously the topographical or historical details in John's Gospel. Scholars ignored them or preferred to see them as symbolic because surely John was not concerned with mundane matters. The more skeptical said that it was wrong in many cases.
So it may come as a surprise to readers that many archaeological discoveries match up with the historical assumptions in this spiritual Gospel. Many scholars now take John's topography and other down-to-earth matters seriously. Archaeology has turned the tide.
It's chock full o' links to check out. Seems like a decent enough article.