|Subject: Re: francs into euros|
If it's still possible, the only place to do it is the main branch of the Bank of France. It's located just a few blocks from the Louvre. You can have your hotel concierge look up the address - I can walk there from memory - but sorry, don't recall the name of the street.
Go in there during normal banking hours and go to the currency exchange window. Some francs can still be exchanged, some cannot.