Short version: a wooden postbox outdoors. Fuller description: A light-brown wooden postbox on a pavement area. Behind it, a city building with glass arch, a tree, a bench, bikes parked in bike stands. Sky overcast. Above the postbox, a sign saying Pssst. On the postbox above the flap, an illustration of an ear with soundwaves showing it listening to something. On the flap, the words Lift and Listen. Written below, a description of the project as roughly translated and summed up by me in the toot, and credits for the various groups involved. This is in Aarhus, Denmark. The postbox was in concert hall park recently, I think it moves around.
https://files.mastodon.green/media_attachments/files/117/264/318/437/993/102/original/b230ac91fb709a02.jpg