DraftSight

DraftSight is a professional, 2D CAD product, open for all users who want to draw, edit, and view DWG file.

DraftSight is free product of Dassault Systems which also have many commercial CAD products, like SolidWorks

DraftSight can be downloaded from Dassault Systems' official website or from   CNet

Compatible with the following operating systems: Windows (64 bit and 32 bit), Mac, and Linux (Fedora and Ubuntu)