Answer:
Richard Long, “A Line Made By Walking” (1967) ...
Michael Heizer, “Double Negative” (1969) ...
Robert Smithson, “Spiral Jetty” (1970) ...
Nancy Holt, “Sun Tunnels” (1976) ...
Walter de Maria, “The Lightning Field” (1977) ...
Marinus Boezem, “The Green Cathedral” (1987) ...
Andrew Rogers, “Bunjil Geoglyph” (2006)
