ABSTRACT
Within the context of the restoration principles, that claims for preserving the whole integrity of the monument, it should be well accepted that we should not rush in deciding the stabilizing measures until the behavior of the monument is properly understood. This requires a long term monitoring aimed at identifying the causes of movements, their potential increase in rate and requires to distinguish the normal physiological behavior from deviations. In addition, these observations can be complemented with experimental identification analyses, performed in the presence of ambient vibration, that allow to explore in a rather effective way the response of the structure and its interaction with the soil. This chapter is intended to contribute on the subject of preservation of historic towers by highlighting, throughout the well documented case history of the Ghirlandina tower, the role of continuous dynamic monitoring and identification techniques for an accurate assessment of the response of the structure, including its interaction with the foundation soil.
