the files were created in Autocad without any coordinate values nor a projection file. But I wish to import this in to ArcGIS as one of the layer on a map It is not possible if they are projectionless on creation unless you can define an origin and then use the CAD units. Hi. identify any permanent features either from google earth or arcgis basemap. For example road intersection, edge of building etc. try to find more than 5 features and must be scattered on your basemap. Then, generate the point into vector. Next use spatial adjustment from arcgis tool. hope this may help you I am agree with the suggestion of Haider Al- Ani. please fallow this methodology and solve your problem. Assuming while in AUTOCAD you have the coordinate system. Using Global Mapper to convert to Esri shapefile there yoy redefine the coordinate system in a wizard that prompts you to. Opening the file in ArcGIS the needful is just assigning that coordinate system. Assigning not defining. If you have already import and georefference the data in ArcGIS be sure a lot of technical problems could occure. Overlapping of polygones, interrupted lines, etc. Use the Topology Tool of ArcGIS to locate them. Source.