This book originates from the ISPRS/CIPA Workshop "3D-ARCH 2017 - 3D Virtual Reconstruction and Visualization of Complex Architectures", which was held in March 2017 in Nafplio, Greece. The main workshop's scope was to bring together scientists, developers and advanced users in 3D surveying and data processing and to encourage cooperation and practice sharing in the various fields where 3D technologies are nowadays used. The workshop focused primarily on multi-source and multi-sensors approaches, low-cost sensors and open-source algorithms for terrestrial 3D modelling, automation in data registration, image matching and 3D reconstruction, point cloud analysis, 4D modelling, BIM/HBIM and procedural modelling, accuracy requirement and assessment in 3D reconstructions, 3D applications in terrestrial and underwater environments, Virtual and Augmented Reality (VR/AR) applied to the visualization and conservation of complex architectures and heritage. The most exciting and innovative papers presented at the workshop were selected to be extended and included in this cornerstone collection.