Hello, world! is an installation for the virtual globe of the software Google Earth (carried out by students from the Bauhaus-University in Weimar, Germany):

A Semacode measuring 160 x 160 meters was mown into a wheat field near the town of Ilmenau in the Land Thuringia. The code consists of 18 x 18 bright and dark squares producing decoded the phrase “Hello, world!”. The project was realized in May 2006 and photographs were taken of it during a picture flight in the following month.

See the weblog of the project here. Why do I blog this? I may be an old fart about this project but I found interesting to have a visual code (i.e. a connector between the first world and the second "virtual" world) of such dimensions.