Since the Mixed Reality (MR) Microsoft HoloLens headset was released in 2016, potential applications of MR processing became highly apparent upon sale, partially in academia and the manufacturing industry. However, important issues with the HoloLens restricted Field Of View (FOV) to a window of 35 degrees was evident to the users (Bimber & Bruns, 2011). This optical limitation has resulted in losing pre-set functions and visualisations in the AR application window. This paper presents an innovative methodology in designing a spatial User Interface (UI), to traverse the adverse effects associated with the HoloLens’ narrow FOV. The spatial UI is a crucial element towards developing a museum based MR system, which was evaluated by nine experts in Human-Computer interaction (HCI), visual communication and museum studies. Results of this study indicate a positive reaction towards the usability and accessibility of the spatial UI system and the user experience. This approach can help current and future HoloLens developers to extend their application functions without visual restrictions and missing content.