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City
Hall has 17 floors plus an observation deck and three underground
levels.
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 Similar to
many well-known buildings nationwide, the original design of the current City Hall incorporated technology that allowed thin layers of marble to be attached to the face of a building to create a "skin." The marble used in City Hall is a Georgia White marble, giving the building a brilliant white color and conveying a sense of solidity and permanence. This type of thin marble veneer construction is made up of thousands of individual panels.
An unforeseen condition, called hysteresis, affects this type of marble when used in this way. Hysteresis is a term used to describe the deterioration of marble. When a piece of marble is exposed to changes in temperature, slight cracks form among the molecules that hold it together. This cracking varies depending on the grain of the marble. The marble used at City Hall has a "coarse" grain and is more prone to hysteresis than other "fine" grain marbles.
 Because hysteresis is triggered by temperature changes, areas of marble that are exposed to sunlight and general weathering are more susceptible to the condition than areas that are not exposed. As a result, individual marble
 panels deteriorate at different rates, with the exterior face of a panel deteriorating at a faster rate than the interior face, ultimately causing the panels to cup and bow. Furthermore, edges of marble exposed to a great deal of weathering experience very pronounced, often visible, cracking.
 The cracking
and bowing form stresses within each panel as a result of hysteresis which cause the marble to lose much of its strength. Eventually, the panels become so fragile that they can no longer safely remain on the exterior of a building.
Based on a study commissioned by the City, it was determined that hysteresis was, in fact, present in the marble and that a long-term solution to the problem had to be found. In response to this finding, approximately
5,000 fiberglass  straps and a system of fiberglass corner supports were installed in October 1995 over the face of the building to temporarily insure that all marble panels remained in place.
Over several years new cracks have developed within the marble along the straps. With this progressive deterioration, developing a solution was
crucial both to the appearance of the building and for safety reasons.
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