Switzerland

Switzerland has over 9 million people, with plenty of mountain wilderness remaining. 

https://en.wikipedia.org/wiki/Geography_of_Switzerland 

https://en.wikipedia.org/wiki/Switzerland#Urbanisation

https://en.wikipedia.org/wiki/List_of_cities_in_Switzerland#List_of_towns_and_cities

 https://www.aboutswitzerland.eda.admin.ch/en/a-nation-of-railway-enthusiasts-a-history-of-the-swiss-railways

https://en.wikipedia.org/wiki/History_of_rail_transport_in_Switzerland 

https://en.wikipedia.org/wiki/History_of_rail_transport_in_Switzerland#Z%C3%BCrich_S-Bahn 

https://company.sbb.ch/en/company/about-us/history.html