The posters were uncovered in Clacton, Essex, earlier this week.
Danny Sloggett, 40, spotted the retro signs in Meredith Road and now wants to ensure they do not end up hidden away again.
"They're relics, they're our history and they show off Clacton's power," Mr Sloggett said.
"The royal family used to come here in the 1920s and 30s. Lots of people used to come from London, and things like this are an important part of our history which has been hidden away."
The posters, which advertised Ambrosia, Black Cat cigarettes and a local cafe, are on the side of a building currently occupied by Sheen's Estate Agents.
An employee there said "loads of people" had come to take pictures over the last few days once the signs had been exposed.
On Facebook, one user said the billboards "should be covered with perspex like the Banksy stuff".
"Should definitely restore it and photograph for a museum," wrote another.
Mr Sloggett said he had not yet contacted Tendring District Council about the possibility of preserving the signs as he wanted to build support for his cause before doing so.
"They're amazing things. I know the history of Clacton but it's nice to see it on display," he said.
The BBC was unable to contact the company that owns the modern billboard.

23 May 2016 Last updated at 17:21 BST
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The former owner of BHS, said it was "wholly untrue" that he had tried to pressurise the regulator.
He also attacked statements made by MP Frank Field, calling them "untrue, totally inaccurate and unhelpful".
Sir Philip said: "I would like to apologise sincerely to all the BHS people involved in this sorry affair."
He was responding to press articles suggesting he had been putting pressure on the Pensions Regulator by saying he would help plug the BHS pensions gap if it dropped an investigation into the retail chain's collapse.
He also reacted angrily to statements in the House of Commons on Wednesday by Mr Field, chairman of the Work and Pensions Committee, that Sir Philip was unwilling to reach a pension fund settlement.
"I stated at the [Work and Pensions Select Committee] hearing that it was my intention to try to find a solution, which is a voluntary one, and that is still my aim," he said.
"Contrary to all the coverage I have been working on this issue on a daily basis."
He said that he and his executives, had been co-operating with the Pensions Regulator for some 17 to 18 months.
"Since before the company was sold in March 2015, it was always our intention to find a plan for the BHS pensioners that was better than the Pension Protection Fund and that remains the case today," he said.
The retail tycoon sold BHS for a £1 just over a year before it went bust in April with a pension deficit of £571m.
Advertising billboards thought to be from the 1920s discovered behind a modern hoarding should be preserved "for all to see", a blogger has said.
[NEXT_CONCEPT]
New Turkish Prime Minister Binali Yildirim's political career began while he managed Istanbul's ferry bus network at a time when current President Recep Tayyip Erdogan was mayor.
[NEXT_CONCEPT]
Sir Philip Green has hit back at suggestions that he is attempting to "blackmail" the Pensions Regulator over plugging the £571m BHS pension deficit.