In this paper, we present LAMP3D, a system for the locationaware presentation of VRML content on mobile devices. We explore the application of LAMP3D in tourist mobile guides: the system is used to provide tourists with a 3D visualization of the environment they are exploring, synchronized with the physical world through the use of GPS data; tourists can easily obtain information on the objects they see in the real world by directly selecting them in the VRML world. We discuss the design and development of the system and report about the feedback obtained from the informal user testing we carried out. CR Categories: H.5.1 [Information interfaces and presentation]: Multimedia Information Systems – Artificial, augmented, and virtual realities. H.5.2 [Information interfaces and presentation]: User Interfaces – Interaction styles, evaluation. I.3.6 [Computer graphics]: Methodology and techniques – Interaction techniques.