Green’s Dictionary of Slang

Coalopolis n.

[Newcastle being one of the country’s major coal-mining areas]

(Aus.) Newcastle, NSW.

[Aus]Sydney Sportsman (Surry Hills, NSW) 3 Feb. 6/1: Charlie Frost would like to fight Ed Jessop in Newcastle [...] In Coalopolis the pair would probably draw as big a house as did M’Call and Scanlan.