The final draft was approved only dome in 1705 year. Construction of the cathedral was already at an advanced stage. Dome consisted of three main parts. The first one is a drum (drum) supporting the second dome is essential, while the third lighthouse wieńczą whole. Each element is designed to best distribute the weight. For example, the drum appears to be an open structure, on a thin ring of columns, and a regular spacing between them are filled with decorated płycinami. After him, however, are the solid przypory whose task is to transfer the burden of eight columns dome rising in the center of the cathedral and on the external wall.