This research constructs the virtual environment of a multi-floor building and provides some navigation assistance to enhance the navigation experience of users in the virtual environment. Based on the 2D architectural floor plans and photographs of Engineering and Information Technology Complex (EITC), a virtual environment of the multi-floor building is created using visualization modeling. Geometric modeling, texture mapping, and lighting procedures are employed to increase the visual effect. Two navigation assistance functions, walking through and optimal path navigation guiding tour, developed in the virtual environment helps users navigating in the virtual environment. Walking through allows users to navigate freely to obtain the spatial and geographical information of the virtual environment. Optimal path navigation guiding tour function leads users moving from a specified start position to the destination position along the optimal path. An improved shortest path algorithm is used for calculating the optimal path.