The Turism bureau of Portugal and the agency MSTF Partners found a great way to truly integrate QR in the street. Using the ancient Portuguese art of decorated cobblestones, it placed a QR code in Lisbon district, using black and white stones in place of pixels. When scanned, it leads to content around Portugal’s history and culture, or, when similar art is scanned in any of the cities outside of Portugal, it leads to an offer of a free night in Lisbon.
The only question you might ask is whether, after the initial PR moment has faded, the code isn’t too stealthy for discovery.