You will link another project into this project.
In most cases, you should select Auto - Origin to Origin.
If the current project uses shared coordinates, select Auto - By Shared Coordinates. See Shared Positioning.
See Import and Link Options for CAD Formats and Revit Models....
If you cannot see the linked project in the drawing area, do the following:
This setting ensures that the view displays elements for all disciplines (architectural, structural, mechanical, and electrical).
You can select the linked model in a view and drag, copy, paste, move, and rotate it.
You can also monitor grids, levels, and other essential elements in the linked project. See Multi-Discipline Coordination.