As of March 2025, Autodesk has officially discontinued activation services for the 2016 version. While the software is no longer available on standard product download pages, users with existing licenses or specific needs can attempt the following: Download Link for Civil 3D 2016
If you have an active Autodesk account with a legacy license or an education plan that previously authorized this version, you can download it through the Autodesk Virtual Agent: autocad civil 3d 2016 download