The pilgrimage in the work ties all of the stories together and may be considered a representation of Christians' striving for heaven, despite weaknesses, disagreement, and diversity of opinion.
However, the Miller's interruption makes it clear that this structure will be abandoned in favour of a free and open exchange of stories among all classes present.
You can take a tour of the Cathedral these take an hour — check ahead for times or meander around the cathedral and its grounds with a self-guided audio tour.