dwg - Wikipedia
https://en.wikipedia.org/wiki/.dwg
DWG (from drawing) is a proprietary binary file format used for storing two- and three- dimensional design data and metadata. It is the native format for several CAD packages including DraftSight, AutoCAD, BricsCAD, IntelliCAD (and its variants)...
DWG models download, free CAD Blocks | AutoCAD Drawings
https://dwgmodels.com/
AutoCAD library of DWG models, free download high quality CAD Blocks. Elegant architecture and design.
DWGSee - Free DWG Viewer
https://www.dwgsee.com/
A light and fast DWG viewer & editor, designed to browse, view, measure, markup, edit and print DWG/DXF/DWF files. Supports latest AutoCAD 2020 drawings.