The Golomb graph is a unit-distance graph discovered around 1960-1965 by Golomb (Soifer 2008, p. 19).
It is implemented in the Wolfram Language as GraphData["GolombGraph"].
A non-unit-distance planar graph drawing is illustrated above.
The Golomb graph has chromatic number 4 (as does the Moser spindle), meaning the chromatic number of the plane must be at least four, thus establishing a lower bound on the Hadwiger-Nelson problem. After a more than 50-year gap, the first unit-distance graph raising this bound (one of the de Grey graphs with chromatic number 5) was constructed by de Grey (2018).
