We are about to replace the original belvedere (rotted and blown down decades ago) on our 1889 Victorian house in Austin, Texas.  It is essentially a gazebo built on top of the house.  The basic framing is 20 5 1/2″ x 5 1/2″ x about 11′ posts (three per corner and two per middle of each side) with a ballustrade on all four sides.  It measures 16′ x 16′, with a peaked hipped roof.   It rests on a platform on the roof (but will have its own deck) about sixty feet off the ground.  We’re considering building it largely on the ground and hoisting it to the roof with a crane.  I’m looking for advice on two points.  One is general construction–whether to build it on the ground or in place, and tips on how to do it.  The other is the type of wood, especially for the posts.  Durability and decay resistance are the primary goals, with stability of the wood second.  The wood must hold paint well.  We’re considering treated pine and cypress.  Cost of the wood is not a big factor.  Thanks, Hugh Lowe