I have mixed feelings about Le Corbusier’s architecture (to say nothing of his urban planning philosophy - he clearly influenced Robert Moses), but I think the UN Secretariat building was one of his successes.

An aside: If you look at the full resolution version (downloadable on flickr), you can see the HF amateur radio antenna on the roof. Nerds are everywhere, even/especially at the UN. There’s also a family taking a group picture on the street in front.