The work of American sculptor Walter De Maria is very unique and distinctive.
In 1977, on an area of Frederick in the German city of Kassel was set rig.
For 79 days, she drilled a well depth of one kilometer ...
Then lowered into the hole brass rod diameter of 5 cm and a length of 1 kilometer
And all this is covered up massive plate with a hole in the center.
Today it looks like this: