This paper proposes a high-level augmented reality interface toolkit that allows the combination of audio-visual information with a real world environment in an easy and interactive way. The system is based on MFC libraries, OpenGL, OpenAL, Microsoft Vision SDK and the vision tracking libraries from the well known ARToolKit. Simple and cost effective hardware complements the software solution. This AR interface toolkit can be used as an exemplar for the development of other applications. Users can interact with the presented information in several different ways. Realistic augmentation is also supported such as soft and hard shadows, without sacrificing the overall efficiency of the system. To illustrate the feasibility of our AR interface toolkit a cultural heritage application for museum environments is briefly presented.