Following recent demolition work in Lincoln, it is now possible to identify (for the first time here) Wilde's lecture venue in Lincoln, which for over a century had been unknown or misinterpreted.
One source of confusion is that the theater where Wilde lectured was known as "City Hall"—with the name used in the sense of a music or concert hall, (e.g. as in Carnegie Hall). The lecture did not take place at a city hall in the usual sense of a municipal building.
For more on the verification of the venue see the feature Not That City Hall.