Global Mapper will display multiple data sets in correct geospatial positions; adjacent data sets can be mosaic-ed, and vector data can be displayed on top of raster and elevation data.
Choose Open
Data File(s) icon from the Toolbar and select files.
The registered version Global Mapper has no limit on the number of overlays that can be viewed simultaneously. A maximum of four files of any type may be viewed simultaneously in the unregistered version of Global Mapper.
All of the files under a directory, and all sub-directories under that directory, that match a specified filename mask can be loaded at once. You can do this using the Open All Files in a Directory Tree File menu command.