For three decades, Ink has treated the passenger journey as a media channel - building the stories, screens and magazines that occupy the rare moments when travellers actually look up.
JCDecaux turned a piece of civic furniture into a 60-year business model. Now its hardest trick is making a million physical advertising panels behave like software without making cities feel like websites.
Clear Channel Outdoor still rents rectangles beside roads and inside airports. But the more revealing business is the machinery behind them - audience data, automated buying and proof that a physical ad did something.