Which European cities are a must-visit while backpacking?

Greece, i went their with my hubby and the hospitality was amazing.. they have quiet a few museams now that look so high techy and everything. I went clothes shopping there since i heard EU fashion is 1-2 years ahead of America. But you must see for yourself. I was suprised there's so many blonde blue eyed people there... I have been to Germany and Norway and I couldn't believe how many naturally blonde blue eyed people Greece has! I'm Russian and I looked like a native indian in front of them ahahah so strange i tell you! maybe because 80% of Greece is mountainous? but really you should visit Macedonia and i mean the city (the one located inside Greece, not the country on top of Greece). Have fun