Published on the book: Augmented Reality, some emerging application areas, ISBN: 978-953-307-422-1. --- In this work, key aspects of AR in construction sites are faced and a construction AR aided inspecting system is proposed and tested. Real world would appear in the background with the construction plans superimposed, allowing users not only to inspect all the visible elements of a given building, but also to guarantee that these elements are built in the correct place and orientation. Besides merging computer-generated information from CAD (Computer Aided Design) plans and real images of the building process, the proposed system allows users to add annotation, comment or errors as the building process is completed. Since this information is saved in DXF (Drawing Exchange Format) format, a new layer can be added to the original CAD plans including the accomplished modifications. Therefore, users can import original CAD plans to be visualized on real environments, to perform the required modifications using actual image from the current states of the construction site and, finally, to save the final results in the original CAD file. The aim of this new way of working is not to replace the usual CAD applications, but to add a new, more intuitive, faster and reliable stage, in the testing, assessment and modification of plans for construction and reconstruction projects.