  The unbinding properties of an interface near structured wedges are
investigated by discrete models with short range interactions. The calculations
demonstrate that interface unbinding take place in two stages: $i$) a
continuous filling--like transition in the pure wedge--like parts of the
structure; $ii$) a conclusive discontinuous unbinding. In 2$D$ an exact
transfer matrix approach allows to extract the whole interface phase diagram
and the precise mechanism at the basis of the phenomenon. The Metropolis Monte
Carlo simulations performed in 3$D$ reveal an analogous behavior. The emerging
scenario allows to shed new light onto the problem of wetting of geometrically
rough walls.
