The deal with the city council includes more than 300 free standing ad panels, as well as a series of pedestrian tourist signs that include more than 200 maps, information panels and finger posts.
The outdoor contractor has partnered with design companies Applied Information Group and Lacock Gullam as it develops the sites.
Barry Sayer, chief executive of Clear Channel Outdoor, said his firm would develop its street furniture "in line with the topography and character of this vibrant city".