That's why I've said "outside of the former Soviet Union", inside the former Soviet Union there are cities which can compete with Belgrade on the brutalist front, from what I was able to see from IG Sankt Petersburg and Kyiv are quite interesting on that front. To say nothing of the brutalist Soviet bus stations which deserve an architectural category/style all for themselves [1]
[1] https://www.theguardian.com/artanddesign/gallery/2015/sep/02...