Glass House, there are 13 other structures on the 47-acre property (Johnson built a new structure roughly every ten years) including his library and study (above). There are also a few site specific installations, like the concrete structure by Donald Judd (below).
Brick House (below) to serve as a guest quarters and art gallery.
painting gallery (below) and sculpture gallery.
Ghost House, originally built to encase a collection of lilies. Now it fills with the local grasses until you can't even distinguish it from the surrounding landscape.
More photos here.
© all photos by me.