The importance of 3D metric documentation of cultural and natural heritage is well recognized at the international level, and there is increasing pressure to digitally record heritage sites and objects in three dimensions (3D). The continuous development of new recording sensors, data capture methodologies, and multi-resolution 3D representation as well as the improvement of existing methods can contribute significantly to the conservation and presentation of heritage. This article reviews some important 3D documentation issues and the actual 3D modeling techniques with their limitations and potentialities. Particular attention will be given to reality-based surveying techniques for visible sites and objects with different examples reported throughout the article.