A.I. Cultural Guide" combines VR and AR technologies with artificial intelligence, aiming to provide intelligent guided services for dementia patients, assisting them in cognitive training to slow the progression of their condition. Considering the mobility challenges faced by the elderly and the environmental changes caused by urban redevelopment in Hong Kong, we utilize VR technology to create an immersive experience that allows seniors to revisit familiar streets and landmarks from the past without leaving their homes. Through a mobile virtual exhibition, they can safely and comfortably relive past life scenes, evoking precious memories. At the same time, we have produced interactive AR postcards. Seniors simply need to scan the postcards with their smartphones to enjoy introductions to attractions, historical stories, audio files, and real images, even participating in simple interactive games. These postcards not only stimulate the memory and cognitive abilities of the elderly but also create common topics for discussion with caregivers, enhancing communication and training language use. "A.I. Cultural Guide" adds an interactive element to reminiscence therapy. Through the combination of VR scenes and AR technology, seniors can reflect on their life experiences, share stories, and enhance emotional communication in an immersive experience. This novel and engaging approach not only increases elderly participation but also helps slow down cognitive decline. The operation of the system is straightforward; both seniors and caregivers can experience it using smartphones or tablets, lowering the technical barrier. Our AI technology can also continuously update content based on feedback and interests from the elderly, maintaining freshness and appeal. In summary, "A.I. Cultural Guide" integrates advanced technology with humanistic care, providing a new avenue for cognitive training for dementia patients while contributing to the well-being of seniors and social harmony. We hope this project will promote the development of elderly-friendly technology, allowing more seniors to enjoy the convenience and joy that technology brings.