Changing Elevations of All Levels

***update, this is described better here***

Importing a model from RAMSteel plays havoc with building elevations (height), so we need an easy way to modify the elevation of all the floor levels at once.

I'm just gonna steal this straight from Revit OpEd's site:

Tools > Project Position/Orientation > Relocate This Project will allow you to "move" your project up to the elevation you specify. In reality it doesn't go anywhere, just tells Revit that zero is really 100 ft. If you load a civil file with real 3D elevation data it will still be above your building so you'll have to move it down to show the correct position relative to the building.

From Help:
To see the results of relocating and rotating a project, the host project must contain linked instances at shared locations. The relocate and rotate functions will modify the position of all elements in the project and any import instances that are not linked. In addition, any linked instances that are not at shared locations move relative to all linked instances at shared locations.


References:
http://revitoped.blogspot.com/2006/06/true-elevation-and-position.html