I have placed a filled region in Revit but it has lines around the outside. Can I remove the lines? If so how do I do it?
Yes you can remove the lines around filled regions
First pick the filled region you wish to edit.
Now select the Ribbon Modify|Details Items > Mode > Edit Boundary.
Pick all the lines you wish to change.
Select the Ribbon Modify|Details Items > Edit Boundary > Line Styles, select <Invisible Lines> from the Type Selector.
Click Finish Sketch (Green tick on the Ribbon).