This work presents a mixed reality (MR) system designed to explore inaccessible cultural heritage sites through immersive and interactive experiences. The application features two versions: an asynchronous personalized guided system offering interactions tailored to individual users’ requests and a synchronous guided system providing a shared, collective navigation experience for all users. Both versions integrate innovative mechanics that allow users to explore virtual recreations of cultural sites. Multi-user functionality ensures the visibility of other users as avatars in the virtual environment, enabling collaborative exploration. The proposed application offers a GPS localization system for on-site experiences and a non-location-dependent option for remote settings. A user evaluation was conducted to assess the effectiveness and engagement of the system, providing insights into user preferences and the potential for MR technologies in preserving and promoting cultural heritage. The results highlight the application’s impact on accessibility, immersion, and multi-user interaction, paving the way for further innovation in MR cultural heritage exploration.