(GMT)07 JAN 2017 ERJO:
How far you can travel by train from Paris in a day. Follow the link and you can find dozens of the maps for other European cities.
In France, almost half of the country is accessible in less than four hours from Paris.
A train enthusiast in the US, Peter Kerpedjiev, a postdoctoral fellow at Harvard Medical School produced a series of fascinating maps that reveal how far it’s possible to travel in just under a day from various European cities. The map is based on statistics from the Swiss public transport system, the guy mined all the stats and produced those maps