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.
For detailed visitor information see the Avallon travel guide. Avallon is situated in the Yonne (Burgundy region) in the eastern-center of France at 43 km from Auxerre, the department capital. (General information: Avallon is 191 km from Paris). Popular places to visit nearby include Vezelay at 13 km and Noyers-sur-Serein at 24 km.