At the end of the 15th C the city was surrounded by a brick wall. There were entrance gates, defense towers and a canal, the Singel gracht. This is the Schreierstoren. The name is derived from Schreyhoeckstoren, meaning the sharp angle of the tower. However the Dutch word schreien also means to cry, so we call it the tower of tears or the weeping tower. From this tower the wives of the sailors waved good bye to their husbands when they set sail. One of the people leaving from the tower was Henry Hudson, there is a plaque.