We study the interplay between internal gravity waves and topography. When internal waves are impinging onto a sloping bed, striking phenomena are expected to occur close to the slope due to the unusual reflection properties. We have designed several internal wave generators to study experimentally this reflection. We have also designed a simple laboratory experiment to study the internal tide generation. We consider a steep continental shelf in an oscillating flow, for which an internal tide is shown to be emitted from the critical point. We discuss the dependence of the width of the emitted beam on the local curvature of topography and on the viscosity, by drawing an analogy with an oscillating cylinder in a static fluid.