People usually post pictures and videos of nature related things in this thread.
But I think that urban sceneries like this can be quite serene as well.
There is this one metro station, which is usually almost empty during nights.
You can walk the whole journey to the platform without seeing anyone on the way.
The only sounds that you can hear are the escalators silently humming and some infrequent calm beeping to guide the blind.
The air feels cool and nice, the smell of a tunnel can be smelled, which is a rather pleasant smell.