Wood post pergolas have a pressure treated post to allow direct ground contact.  The oak post begins with a pressure treated 6x6 post, then wraps it with rough-sawn white oak to give it an authentic heavy timber appearance.  The oak post pergola also has a rough-sawn oak top (other pergolas use pressure treated southern yellow pine tops).  Pergolas may be stained or painted to fit your specific needs.

Below:  10x10 treated wood post pergola

Below:  8x14 treated wood post pergola with floor and stain

Below:  10x10 wood post pergola in oak