But the demolition of a row of pre-war shops in Sydney's inner west provided an intriguing glimpse into life in Sydney in the early 20th century.

Exposed for the first time in decades, a blue and white sign advertising The Sydney Morning Herald looks like it could have been painted last week, its colours vibrant despite its age.

A hand-painted sign for The Sydney Morning Herald was uncovered by a demolition crew in Campsie. Photo: Supplied

Painted above is a faded, chipped sign for a rival newspaper that has not weathered the passage of time.

The ghost sign advertising The Sydney Morning Herald was on the side of a building that used to operate as a newsagency, with a residence above it.

It was uncovered by builders demolishing a row of shops in Beamish Street, Campsie.

Based on information from the 1928 Canterbury Valuation books, a spokeswoman for The City of Canterbury Bankstown said: "We know it was already there in 1926, but we don't have an exact date of when it was built."

"As to who painted the sign, we have found old tenders in the SMH to paint the property owned by R Moller," she added.

The newspaper advertisement attracted a number of photographers when it was revealed on November 10, including a reader who estimated the sign was revealed for about a day before the demolition crew consigned it to rubble.

Old hand-painted advertising signs, or ghost signs, in Australia date back as far back as the 1880s, according to the Ghost Signs website, with the painters of these signs known as "wall dogs".

A ghost sign on the wall of a former corner store in Annandale. Photo: Steven Siewert

Conserving Historic Signs, NSW Heritage Guidelines contains many examples of ghost signs, which it said can evoke a "picture of the past, at the top level displaying the cultural climate of a particular era, either economically, politically, socially, scientifically.

"This can be seen through images of election campaigns, war notices for help in the war effort, graffiti through to advertising products like soap and tobacco."

A ghost sign on the wall of an old corner store on Junction Road, Summer Hill. Photo: Steven Siewert

"This was also a time when media was limited to radio and newsprint, with the odd film," she said. "Thus, these large-scale mural advertisements were a striking and visual form of marketing and communication for businesses. One wonders whether they were appreciated at the time or seen as a form of visual pollution."

Dr Bishop said hand-painted advertising signs were worthy of preservation as a form of art "and as a reminder of a time when people looked around them rather than at their phone screens - and businesses communicated with people in large format rather than by tweet".

A ghost sign on George Street after the demolition of buildings on the old Menzies Hotel site. Photo: Steven Siewert

In September, the demolition of a 1960s tower block at the old Menzies Hotel at Wynyard briefly exposed the advertising facade of a gentleman's department store that was once a landmark of George Street.

The building known as Beneficial House is heritage listed, which encompasses the sign, but it was soon lost to view again with the construction next door of a new tower at the Wynyard station upgrade.