What definition of city are we going by? If you mean a city as large as Constantinople then no, as there were no cities in Europe bigger than Constantinople. In fact, there would have been no larger cities in the world outside of China. In northern and western Europe, cities were very small in comparison to cities in the Middle East, India and China. A place like London would only have a population in the low tens-of-thousands, as the populations were spread out and restricted from moving due to Feudalism, and that is the higher end city sizes. In places like Denmark, Sweden or Norway the largest population centers would have similar or lower numbers, and none of these places would have anything close in scale to the grand architecture of Hagia Sophia. Now, if we are going by a very generous definition of city, then as a noble he would have certainly spent time in the largest cities in Scandinavia, and many of his companions probably would have spent time in these cities as well. Its also possible that some of these mercenaries would have traveled around Europe to find work, and may have been too some of the larger cities, like Paris or Kiev, that would have had populations at least on the same magnitude as Constantinople, though still much smaller in size.