Architecture and tradition
The concrete imagery of architecture is welcomed by the title which orients the story under the silent watch of the buildings that serve as the setting. On top of this concrete imagery, there are abstract associations with the power structures preserved within those important and glorious buildings, and from there, the imagery descends into time and particular circumstance. Part of the imagery of the building is the lives of the people contained in those spaces, people who will pass away in time; that is the promise of the imagery from the first scene where the reader learns about the death of a bishop.
Romance and marriage
If authority structures are what humans share most in common with their concrete environments, then the antithesis to those unaffected façades would be the passion of the congregants' personal lives. Those social lives are shaped almost entirely on the game of marriage. Married couples very quickly have sons and daughters who need to be matched up responsibly, and single people struggle to know how to make that happen themselves, having only their instincts to rely upon. In this subtle imagery of social dance, comments are made about gender role.
Authority structures
The imagery of abstract human authority figures is an important part of making the architecture relevant to the personal lives of the people in town. The reason that churches and government buildings matter in the community is because those authority systems have regular and consistent influence on the daily life of the town. When Bishop Proudie's wife nags him, that has a negative effect on the influence of the church on the people and they begin to complain to him about her. The imagery is a major part of the plot, because people react to their authorities.
Polite society
Another important imagery to notice is the way that niceties shape the culture of this community. This is not a time in history where impolite opinions are tolerated for very long, but that makes another kind of abstract imagery, an imagery of plausible deniability. Think about the rules of a sonnet; traditionally, those strictures are imposed to force the poetry to be more poignant and punchy. In this community, political niceties and commonly agreed upon rules for social behavior serve as similar strictures, accentuating the undeniable human passions which emerge from the network of mutual influence.
