In general, I am of the opinion that brutalist buildings (and, really, pretty much all modernist buildings) look their very best at night, especially when well-lit. The HMS/HSPH quads are great at night... one of my favorite spots. The Countway itself is a gem and completely underappreciated, partly, I think, due to its being set back from Huntington. Bonus for the nearly full moon tonight, visible between the Public Health School building and Countway.
The second quadrangle partly out of view is also nicely done. Devoid of people at night, yes, but not every single public space needs to be crammed with pedestrians to make it a great space. Sometimes the silence and quietude is the superior ethic. I don't even know much about the big, hulking Kresge Building on the right there, but I know I like it, too.