Philly has the most public murals of any city in the country, thanks to the Mural Arts Program. For all our murals, though, Philly can’t claim to have the largest public mural in the country. Currently, the “Omaha Mural Project: Fertile Ground” is the largest mural in America. It’s eight stories high and longer than a football field (34,000 sq. feet). In Philly, though, some folks—including Streets Dept, a blog covering street art in the city—are trying to get Mayor Nutter’s attention because they want to put a mural on the back of the PSFS building. They’ve started a petition and aim to get 5,000 signatures. As it stands, one side of the 491-foot building is painted black.