French language Q&A Forum

Normally, I think of using the preposition "à " when referring to a city.  In this passage, they land in (à) Paris but they take the train to (pour) Florence.  I am guessing that Florence is not an exception as a city but rather one takes the train for or to a city using the preposition, pour, instead of à.  Is that correct?

Hello all,

I've seen several French expressions/phrases where there is no definite or indefinite article, where there would be one in English. 

For example. C'est bon signe meaning that's A good sign, j'ai rencard avec lui meaning I have AN appointment with him.

Is there a general rule that explains this ?  

Thanks,

Jean