The H-Factor

Q: How do you view Revit files without buying Revit? 

A: From Autodesk – Download the Revit program and run it in Demo mode. Demo install can function as a viewer with no expiration. Demo mode
allows all features of Revit, but you cannot save, plot or export
your
project after changes are made. Demo mode serves as a no-cost viewer for
yourself or team members who need to view, plot, and export projects without
changing them.

—
Jeff Hanson
Autodesk – AEC Technical
Publications
Manchester, NH

You can download Revit at Revit MEP Download