DOI: 10.7764/RDLC.16.1.158This paper presents the methodology and results of the geometric monitoring of a leaning tower (Santa María la Blanca church in Agoncillo, La Rioja, Spain) with surveying techniques. Throughout the period 2007-2014, two types of variations in the geometry of the building have been tracked: those due to a seasonal cycle (winter-summer) and those caused by the progressive increase in the leaning of the tower. The text describes the distribution of the control points, the fieldwork, the computation strategy and the way to ensure that the results are significant. By way of conclusion, this work discusses the applicability of these techniques to the monitoring of historic buildings.