The Australian Overland Telegraph Line was an electrical telegraph system for sending messages the 3200 kilometres between Darwin, in what is now the Northern Territory of Australia, and Adelaide, the capital of South Australia. Completed in 1872, it allowed fast communication between Australia and the rest of the world. When it was linked to the Java-to-Darwin submarine telegraph cable several months later, the communication time with Europe dropped from months to hours; Australia was no longer so isolated from the rest of the world. The line was one of the great engineering feats of 19th-century Australia and probably the most significant milestone in the history of telegraphy in Australia.

Darwin is the capital city of the Northern Territory, Australia. The city has nearly 53% of the Northern Territory's population, with 139,902 at the 2021 census. It is the smallest, wettest, and most northerly of the Australian capital cities and serves as the Top End's regional centre.