The tower was first mentioned in 1330 as the Sand Tower (the name apparently derives from the sand hills opposite the tower).[1] The entrance to the tower was five metres (16 ft) above the ground and the building could only be entered by a narrow staircase. During the Swedish attack on Poland of 1621, the entire tower was destroyed, except the basement, on which the now visible Powder Tower was built in 1650. In horizontal cross-section, the tower was horseshoe-shaped: in some places, the three-metre (9.8 ft) thick wall of the tower faced the outskirts, while the wall on the city side was made of wood (bricks at the time were an expensive building material).