Virtual reality technology is developing quickly, opening up new possibilities that have an impact on multidisciplinary work on cultural heritage sites, especially for those who are lost and are in ruins by passing times and ages. Its uses and benefits as a touristic product contribute to the economy and development of tourist destinations. The study aims to examine the ability of applying virtual reality technology to one of the most valuable lost heritage sites in Cairo, which is al-Qaṭāʾi city. The Tulunid capital was the third historical one during the Islamic era. It was enriched by wonderful buildings and running life until its burning in 905 A.D. by the Abbasid caliphate in his trail to re-control Egypt. The study presents an imagination of the city by presenting a case study of the Gate of Lions, which was one of the main old gates of the city, of which we have a full description by the historians of this period of history. The study describes how the life in the city was useful in converting it into virtual reality technology. The research aims to help the growing up of Islamic heritage existence on smart technology plans in Cairo. By presenting an imagination of how the buildings were designed and shaped. The city had markets, streets, gates, palaces, and administrative buildings. The research objectives are to provide a theoretical explanation for some lost buildings in the city, which could be a base for further researches.