A geodesic vertex is a signal / geographical landmark built by engineers to measure the earth. These signs indicate the exact position and are located at the top of the hills, mountains, towers, .. They may also be at ground level or at sea
Its name is given for each vertex does precisely on top of an imaginary triangle with the closest, which in turn form a series of triangles with other geodetic vertices. Each milestone has its own name and has marked the coordinates and altitude compared to sea level.
In this geodesic vertex plate reads: National Geographic Institute. Geodesic vertex. The destruction of this sign is punishable by law.
That phot was taken in the top of the Mine Mountain.
An example of place where this vertex are: here