3D LASER SCANNING AS A CRITICAL ARCHIVE: A MORPHOSTRUCTURAL REASSESSMENT OF THE MOSQUE OF THE DEY IN ALGIERS

Abstract

This article offers a critical reassessment of the Mosque of the Dey in Algiers, based on the cross-analysis of three sources: a three-dimensional survey conducted by terrestrial laser scanning (TLS) in 2019, direct in situ material observations, and Ottoman legal records transcribed by Albert Devoulx. Situated within a building archaeology framework, the study reconstructs the processes of assembly, reuse, and adaptation that governed the construction of this monument, regarded as the last major architectural achievement of Ottoman authority in Algiers. Three key areas are analysed in detail: the north-east wall, the qibla wall, and the minaret. The TLS survey reveals an asymmetry between the base and the upper section of the north-east wall, with irregular over-thicknesses and misalignments pointing to the integration of an earlier substructure. The qibla wall displays a subtle yet significant outward inclination in its upper masonry, while the minaret, visually perceived as hexagonal, is in fact affected by a torsional distortion of its plan, reflecting the cumulative impact of time, use, and structural contingencies. These material singularities, imperceptible to the naked eye, directly resonate with historical sources: the geometric anomalies confirm the rapid expropriations and partial reuse of earlier structures mentioned in legal deeds. The TLS survey, employed as a critical archive, not only exposes hidden morphological anomalies but also clarifies structural discontinuities and contributes to the assessment of seismic vulnerability. By combining 3D digitisation, historical documentation, and architectural analysis, this research advances an interdisciplinary methodology that refines the morphostructural understanding of the monument and promotes a preventive approach to the conservation of architectural heritage.