Medivial Pavilions

[GREEDER at delphi.com]

I have been researching the subject of medivial pavilions to prepare to 
design an build one of my own.  So far I seem to find details on round
pavilions, square pavilions, and rectangular pavilions.  But I was thinking
of making an octangonal pavilion.  So are octagonal pavilions period?
Should I build one any way?  Would it realy matter? (except to the authenticity
police?)I mean it's not that hard to convert an octagonal design into a round design
Other questions:  I have seen designs that use a center pole and designs
that use a frame.  Can anyone relate experiences that would indicate that
one method is prefered over the other?
Of course any other input is apprieciated.
Thanks
Gordon