Facebook ads have appeared on sidewalks across Philly. The city does not like them.

Philadelphia is giving a collective angry face to what appears to be an unapproved marketing campaign for Facebook targeting Philly’s sidewalks.

In a place with tons of street art, in the city that birthed the Toynbee Tiles, people notice what’s around them, even what’s at their feet.

Earlier this week, Conrad Benner, who documents Philly’s street art scene with his popular blog Streets Dept, posted photos on Twitter of what appeared to be Facebook ads — including several for “Facebook Dating” — plastered on sidewalks at intersections around Center City.

He was not happy.

And neither were many other people, some of whom have already taken to defacing them.

Still others easily tore the ads — which appear to be a sort of sticker — off sidewalks like a scab.

City spokesperson Kelly Cofrancisco said in an email that there was no record of Facebook asking for or receiving approval for the ads, and the city can’t speculate where they came from.

“If a company or organization wants to place ads in the public Right of Way, they must go through an approval process that involves the Art Commission,” she wrote.

Facebook did not respond to requests for comment. While the city does not know who installed the sidewalk signs, Cofrancisco said Facebook received approval to place ads on bus shelters for the same campaign.

Benner said he thought it was unlikely that the signs were the work of a street artist trying to make a subtle statement.

“I doubt it was a street artist, particularly because I think if it was, they would’ve looked better,” he said.

Cofrancisco said the city hadn’t been able to determine how many of the ads had been placed. People have reported seeing them beyond Center City, including in Spring Garden and University City.

The ads could be a hazard as well as a nuisance.

“Any sign installed near a footway or street crossing has the ability to be distracting to people using the sidewalk or road which is why approval through the Streets Department is required,” Cofrancisco wrote.

She said Wednesday evening that the city would send a letter to Facebook asking the company to remove the signs within 24 hours. If Facebook fails to do so, the city will remove them and charge Facebook a fee, Cofrancisco said.

By Thursday morning, the ads were disappearing from sidewalks.

While the ads are not permanent, people like Benner do feel that they are an invasion on space in a city landscape already saturated with advertising — from its buildings to its trash cans.

“We can’t let corporations ‘takeover’ our public space,” he said. “The public space is ours, and it should reflect us and serve the greater good, not be used as yet another corporate tool.”