Instead of ads for modern products, the billboards are all old 20th century advertisements. Some, for businesses that no longer exist, such as Mark Foy's department store.
"At Museum Station in Sydney's CBD, Sydney Trains also conserves the legacy of historic commercial advertising as part of the operational station.
"Original signage and authentic reproductions add to the ambience of this historic underground station.
...
"Several railway posters produced during the hey-day of railway advertising between the 1930s and 50s are now recongised as some of the best examples of advertising art produced in Australia from this period."