Raised to save the river Guadarrama, for years this bridge supported road traffic, until the last third of the twentieth century. It is a robust Herrerian bridge, with a single eye formed by a wide arch and built with great granite ashlar. The stirrups are reinforced with buttresses of triangular plant. On the arch and on both facades are distinguished two reliefs that represent a rectangular grids of five bars, the symbol of the martyrdom of San Lorenzo, topped with a handle. Hence this step is also known as Bridge of the Grills.