The Magna Carta influenced the separation of church and state because it prohibited the .church from interfering with the government.
.church from collecting financial contributions.
.monarch from becoming the head of the church.
.monarch from interfering with the church.

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.