3D data production techniques, although increasingly used by archaeologists and Cultural Heritage practitioners, are most often limited to the production of 2D or 3D images. Beyond the modes of visualization of these data, it is necessary to wonder about their possible interactions and uses. Virtual Reality, Augmented Reality, and Mixed Reality, collectively known as eXtended Reality, XR, or Cross Reality, make it possible to envisage natural and/or complex interactions with 3D digital environments. These are physical, tangible, or haptic (i.e., with effort feedback) interactions, which can be understood through different modalities or metaphors, associated with procedures or gestures. These interactions can be integrated by archaeologists in the "operating chain" of an operation (from the ground to the study phase), or be part of a functional reconstitution of the procedures and gestures of the past, in order to help understand an object, a site, or even a human activity. The different case studies presented in this chapter result from collaborations between archaeologists, historians, and computer scientists. They illustrate different interactions in 3D environments, whether they are operational (support for excavation processes) or functional (archaeological objects, human activities of the past).