Huge QR code on the wall of the stairs on MTR <a href="https://en.wikipedia.org/wiki/Admiralty_station" class="extiw" title="w:Admiralty station">Admiralty station</a> platform
<a href="//commons.wikimedia.org/wiki/User:Hawoamz_WLA" title="User:Hawoamz WLA">Hawoamz WLA</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>