Several phenomena take place at the interface between liquid water and the gold (111) surface. For example, it is a widespread system for controlled electrochemical investigations, for the study of molecular conduction and of the interaction between proteins and the solid surfaces in water. Despite this great and interdisciplinary importance, the wettability properties of the gold surface are microscopically not well understood. For example, the contact angle between water and clean gold is zero, thus the gold surface is considered hydrophilic [1]. On the other hand, computational DFT studies on single molecules (or model monolayers) on the gold surface pointed out that the gold-water interaction is very small [2]. The term hydrophobic is often used in this context to classify Au(111). To shed light on the microscopic structure of the water-Au(111) interface, we performed classical molecular dynamics simulations of water on a gold (111) surface. These simulations are based on a force field for gold-water and gold-protein interactions that we have recently developed [3]. It is based on available experimental results and quantum mechanical (DFT and MP2) calculations. Gold polarization effects are also taken into account. In this talk I will discuss the developed force field and the results of our simulations for a neutral gold surface, with particular emphasis on the microscopic nature of the water-gold interface [1] K.W. Bewing, and W. A. Zisman, J. Phys. Chem 69, 4238 (1965). [2] A. Michaelides et al., Phys. Rev. Lett. 90, 216102 (2003). [3] F. Iori, and S. Corni J. Comp. Chem. 29, 1656 (2008); F. Iori et al. J. Comp. Chem. in press.