Immersivity is one of the main features of high quality Virtual Reality experiences. Indeed, much attention has been recently devoted to immersive technologies mainly as a consequence of the widespread adoption of Virtual Reality headsets. Seldomly the term "immersive" is used today to make reference to Augmented Reality technologies. This happens mainly because of the limitation of current AR displays. The talk addresses the concepts of immersivity and presence in the valorization of Cultural Heritage sites by means of advanced Augmented Reality technologies. Specifically, we discuss a work in progress project that employs an immersive Augmented Reality soluion for the valorization of one of the most important monuments in Rome, the Ara Pacis. Hosted in a beautiful building designed by Richard Meyer, Ara Pacis is the symbol of the power exerted by the Augustean lineage across the Roman Empire. The Ara Pacis Augmented Reality solution is developed by ETT in collaboration with Inglobe Technologies for Zetema. It is a first of a kind project based on a unique feature of the ARmedia SDK, namely the support for large scale 3D Object Recognition and Tracking by means of Immersive Virtual Reality Displays - such as the Samsung Gear-VR. The solution allows to navigate thorugh the different POIs of the momunent. Each POI is a gateway to an immersive AR experience that leverages 3D object recognition and tracking to provide visitors with information related to digital reconstructions - both in terms of architecture and socio-historical meaning - of the monument. Large FOV, precision of 3D Tracking, accuracy of CG overlays and personalization of experience are just some of the takeaways of the solution.