GRAMMAR'S RESPONSE. The word premises is always plural, whether you're referring to the whole of the land and the buildings upon it or just part of the mall (or whatever). So you want are, always. Authority: Merriam-Webster's Collegiate Dictionary, Electronic Edition, Version 1.5.
Yonne is a department in the centre of France, in the Burgundy region. The largest city in the department, and its prefecture (capital), is Auxerre.
Ferney-Voltaire is a commune in the Ain department in eastern France. It lies between the Jura mountains and the Swiss border and forms part of the metropolitan area of Geneva.