Colossus of Rhodes - Construction

Construction

Ancient accounts, which differ to some degree, describe the structure as being built with iron tie bars to which brass plates were fixed to form the skin. The interior of the structure, which stood on a 15 meter (50 foot) high white marble pedestal near the Mandraki harbor entrance, was then filled with stone blocks as construction progressed. Other sources place the Colossus on a breakwater in the harbor. The statue itself was over 30 meters (107 ft) tall. Much of the iron and bronze was reforged from the various weapons Demetrius's army left behind, and the abandoned second siege tower may have been used for scaffolding around the lower levels during construction. Upper portions were built with the use of a large earthen ramp. During the building, workers would pile mounds of dirt on the sides of the colossus. Upon completion all of the dirt was removed and the colossus was left to stand alone. After twelve years, in 280 BC, the statue was completed. Preserved in Greek anthologies of poetry is what is believed to be the genuine dedication text for the Colossus.

To you, o Sun, the people of Dorian Rhodes set up this bronze statue reaching to Olympus, when they had pacified the waves of war and crowned their city with the spoils taken from the enemy. Not only over the seas but also on land did they kindle the lovely torch of freedom and independence. For to the descendants of Herakles belongs dominion over sea and land.

Modern engineers have put forward a plausible hypothesis for the statue construction, based on the technology of those days (which was not based on the modern principles of earthquake engineering), and the accounts of Philo and Pliny who both saw and described the remains.

The base pedestal was at least 60 feet (18 m) in diameter and either circular or octagonal. The feet were carved in stone and covered with thin bronze plates riveted together. Eight forged iron bars set in a radiating horizontal position formed the ankles and turned up to follow the lines of the legs while becoming progressively smaller. Individually cast curved bronze plates 60 inches (1,500 mm) square with turned in edges were joined together by rivets through holes formed during casting to form a series of rings. The lower plates were 1-inch (25 mm) in thickness to the knee and 3/4 inch thick from knee to abdomen, while the upper plates were 1/4 to 1/2 inch thick except where additional strength was required at joints such as the shoulder, neck, etc. The legs would need to be filled at least to the knees with stones for stability. Accounts described earthen mounds used to aid construction; however, to reach the top of the statue would have required a mound 300 feet (91 m) in diameter, which exceeded the available land area, so modern engineers have proposed that the abandoned siege towers stripped down would have made efficient scaffolding.

A computer simulation of this construction indicated that an earthquake would have caused a cascading failure of the rivets, causing the statue to break up at the joints while still standing instead of breaking after falling to the ground, as described in second hand accounts. The arms would have been first to separate, followed by the legs. The knees were less likely to break and the ankles' survival would have depended on the quality of the workmanship.