Select the cities which were once subject to Holy Roman Emperor Charles V of the house of Habsburg.
Based upon this map, sourced from a 1912 Cambridge University Press historical atlas via Wikipedia: https://en.wikipedia.org/wiki/Charles_V,_Holy_Roman_Emperor#/media/File:Dominions_House_Habsburg_abdication_Charles_V.jpg
Includes cities which, as part of the Holy Roman Empire, were subject to Charles' indirect/limited rule.
Includes cities that were either lost or gained during his reign.
Charles V died in 1558, and as such cities founded thereafter could not have been subject to him.
Only 4 for me, but I'll give it another try at some point.