A poster is an image with a purpose. It informs, it advertises, it warns or entertains. Collectively, posters form a gallery in the public space. But if there are no longer any messages, if advertising is prohibited and the billboards are abandoned, they reflect only our inner void. Out of the sound of traffic in the street, voice fragments and a concert of whistles and sirens emerges a continuous ominous tone that grows steadily louder, like the sound of approaching aircraft squadrons.