Past midnight. All lights switched off, only illuminated by corridor lights/outside streetlamps, five storeys down. The scene was actually much darker than is implied in these shots; the AF wouldn't work and I couldn't see much through the viewfinder. And amazingly, all were shot handheld!

Typical exposure: ISO 6400, f/2.8, 3.2seconds.
No post-processing other than re-sizing and compression for web.