Mouth of the Douro River. When they saw the port bar, the pilots of the ships were aware that their voyage was not yet finished; the last stage was missing, perhaps one of the most complicated: entry into the Douro. The strong currents and swirls, the treacherous cachopos and boulders of the bar were there to bring the countless disasters that have occurred there throughout the ages to the sailors' sailors. Stories of pain, despair and grief.

Already in times gone by, the bar of Porto was feared by men of the sea as difficult and dangerous. From the Cabedelo channel to Cantareira, the boats went through a real labyrinth between rocks, visible or submerged. During this journey, ships had to pass at least twenty-six stones, starting at the so-called Picão and ending at Pedras da Eira in front of the S. Miguel or Capela do Anjo beam. The difficulty increased during the winter floods, since the opposite current of the river made it extremely difficult to maintain the course of a sailing ship. The sailors overcame these obstacles as they could, guided by various marks and goals. Among them, Pinheiro da Marca was celebrated, on the hill where today are the Gardens of the Crystal Palace. Overthrown by a storm in 1537, it was replaced by a tower in 1542. Another point of greatest use was the chapel of Santa Catarina, built during the reign of D. João I in Lordelo on a high hill next to the Douro. A third point of reference appeared in the center of the channel. It was an Iron Cross erected, on an uncertain date, in a boulder that got its name, and that appeared as a protective sign for sailors and travelers.