According to a theory from an art historian Mladen Pejaković, the design has an intentionally unbalanced elliptical form designated to "follow" the position of the Sun, retaining the functionality of a calendar and sundial. In its beginning, in the time of the Croatian principality, it was used as a royal chapel of the duke's courtyard nearby. The church is that of a central type, it features the Croatian wattle (or simply "troplet") and a carved name of the Croatian župan "Godečaj".
Source: Hrvatska turistička zajednica
Photo by: Juraj Kopač