draw.io - Online diagramming application
DWGFREE - DWGFREE is an online platform that comes with a comprehensive collection of CAD blocks that can be downloaded without the need for registration.
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
CADMAPPER - Instant CAD files for any location on earth
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.
MAPACAD - MAPACAD is an online website that is providing leverage to designers and architectures to have the ability to download CAD map cities that can be directly used in their projects.