Christmas type holiday that can be thrown into any city/town.
The addition of “irrelevant” details adds local colour to a campaign world, giving the impression that the DM has thought very deeply about the history of even the smallest architectural feature.
War of the Roses as a campaign plot. Two noble lines converge somehow, each line thinks it has the rightful claim to the throne. Deciding this long ago was handled by some divine intervention, requiring both houses to come together at some point. They aren't so willing to get together this time. Civil war, or a new king?