What led to the rise of city-states in northern italy during the later middle ages

Following the breaking of the Western Roman empire, many cities began growing due to rich rulers who got in power thanks to their wealth. This led to them gaining independence and sovereignty from their original rulers. What this ultimately led to was an enormous number of city states led by rich merchants and self proclaimed kings.

Currently, as of february 2016, an american traveling in france would be by the exchange rate. the weakness of the euro and the strength of the us dollar means that items in france cost less to an american than they otherwise would. of course, if this trend reverses and the us dollar weakens and the euro strengthens, such as was happening in early 2008, an american traveling in france would have an adverse experience because items would cost relatively more.