It is a coastal city situated on eastern side of Gulf St. Vincent, and is situated on the Adelaide Plains, north of the Fleurieu Peninsula, between the Gulf St. Vincent and the low-lying Mount Lofty Ranges. It is roughly 20 km (12 mi) from the coast to the foothills but sprawls 90 km (56 mi) from Gawler at its northern extent to Sellicks Beach in the south.

Named in honour of Queen Adelaide, the consort of King William IV, the city was founded in 1836 as the planned capital for the only freely-settled British province in Australia. Colonel William Light, one of Adelaide's founding fathers, designed the city and chose its location close to the River Torrens in an area traditionally inhabited by the Kaurna aboriginal peoples. Light's design set out Adelaide in a grid layout, interspaced by wide boulevards and large public squares, and entirely surrounded by parkland. Early Adelaide was shaped by religious freedom and a commitment to political progressivism and civil liberties, which led to world-first reforms. Today Adelaide is known for its many festivals as well as for its wine, arts and sports.