.GBXML File

The gbxml file extension is mainly related to a special XML format called Green Building XML schema.

The gbXML open schema helps facilitate the transfer of building properties stored in 3D building information models (BIM) to engineering analysis tools.

Today, gbXML has the industry support of leading 3D BIM vendors such as Autodesk, Bentley, and Graphisoft.

How to open:

You can view these files using any text editor, however to work with them you have to import them to proper program - like Revit.

How to convert:

Probably can be converted to other formats.