Planners have always held a tight rein on the "look" of Canberra's urban landscape; there are even strict rules governing the size of residents' front fences (the preference is none).
Yet in a city with almost no roadside advertising, it seems no one checked whether the capital's biggest billboard ads were legal.
The growing Canberra Centre has for years displayed huge ads on its walls that face passing traffic, some towering three storeys or more.
The ACT government now says the advertising does not comply with planning laws. Nor does the Environment and Planning Directorate have any records of approving the signs.
However, the centre's management says the ads were designed in accordance with the building's development application, which was approved.
Canberra has two sets of planning regulations – ACT and federal – and both impose tight limits on the size and type of commercial signs in the city.
The National Capital Authority, whose rules take precedence, says the shopping centre sits on land just outside its remit.
The ACT legislation says wall advertising that is higher than two storeys is only permitted if it is "principal signage" – essentially, the name of the building or the business in it, or ads for products made on the site.
Advertising for goods or services sold in the building must be no higher than the second storey, while other ads are allowed only on the ground floor and cannot exceed two square metres.
The office of Planning Minister Mick Gentleman said the Canberra Centre's advertising breached the ACT's signs code. His spokeswoman also said the government had not approved any similarly large signs elsewhere in Canberra.
"To date, [the directorate] has not received any formal complaints about the signs. However, the directorate will give consideration to the application of the code in this area of the city," she said.
"An investigation into the matter will be conducted in due course, with priority reserved for cases that involve life safety and building integrity."
Yet the centre's manager, Karen Noad, said the business believed the signs complied with the development approval granted by the ACT Planning and Land Authority.
"However, we are open to discussing this matter with the planning authority should they wish to do so," she said.
North Canberra Community Council chairman Mike Hettinger was unsurprised no one had explicitly approved the ads, saying ACT planning authorities often failed to enforce their own rules.
"They're either asleep at the wheel or they just don't care. They don't seem to regulate in the way you'd expect a regulator to behave," he said.
"The onus always seems to be on an unpaid member of the public to prove that a development doesn't comply with the law, and to do the government's job for it."