The first four levels are integrated in Pier H, and above that the tower continues on up to a height of nearly 70 meters. From the fifth level up, it was built with the aid of “climbing formwork”. The outer walls of each level were created by pouring concrete directly into the formwork. After the concrete had cured, a 65-meter-tall crane raised it is so work could proceed at the next-higher level. To let it reach the upper levels, the crane’s base was gradually raised to a height of 20 meters. The operators had to do their jobs with millimeter precision at a dizzying height.