World Monuments Fund and UNESCO are collaborating in a project for the conservation and management of the living heritage site of Lalibela, in the Lasta mountains in Ethiopia. The site is still in use today and it is characterized by a series of deep trenches where churches have been carved out from the bedrock in the XII-XIII centuries. One of the first steps in the conservation initiative was the complete re-examination of the graphic documentation available. The pioneering work of architect Sandro Angelini in providing a complete map of the entire site served as a basis for a new complete survey of the site using laser scanners, photogrammetry, GPS and conventional survey methods. This approach was selected for the possibility to recreate 3D digital models of each structure and feature, to provide the conservators with baseline information for subsequent detailed assessments of the state of conservation of these elements, and, eventually, to use the digital data for education and presentation purposes. The paper describes the challenges met in the execution of one of the largest laser scanning project ever conducted in a cultural heritage site.