Well, here's my recipe for the 20k culture win in Regent.
Here's the build order:
Any building providing culture (Temple, Library, Colosseum, Cathedral, University, Reserch Center).
Any building improving shield output (Courthouse, Factory, Police Station, Any Plant).
Any building allowing population growth (Granary, Aqueduct, Hospital) with respect to the limiting factor involved.
Any building improving the stability of your city (Marketplace)
First Comment.. with the city being your Capital.. is there any point to built bolded above?