The Cega, border with Valladolid Nature · Mata de Cuéllar, Tierra de Pinares, Segovia Image of Mata de Cuéllar, not of the place itself. The river Cega runs through the municipal district at 753 metres of altitude and acts as the natural boundary with the province of Valladolid; its bank introduces a corridor of damp vegetation into twenty square kilometres of sands and pinewood. Photo: Rastrojo (CC BY-SA 4.0) What to see and do in Mata de Cuéllar