The goal of this project is to develop a handheld seamless indoor/outdoor positioning platform that consists of several navigation sensors and a visual sensor for navigation and non-navigation applications in city ecosystems. The navigation sensors include an accelerometer, a digital compass, a gyroscope, a high sensitivity GPS receiver, a software GNSS receiver, a WLAN and a Bluetooth chip, while the visual sensor is a digital camera. In addition to the handheld positioning platform, a network consisting of pseudolites, WLAN and Bluetooth base stations will be used for composing a multi-sensor multi-network positioning solution. Fusing navigation sensors, wireless networks and a visual sensor is an innovative approach for seamless indoor/outdoor positioning. Furthermore, all these sensing technologies are miniature in size to meet the design constraints of mobile devices and are suitable for potential applications in city ecosystems. A smartphone-based software and a PC-based software will be developed for exploring the applications. The system will be tested in various city ecosystems for different concepts such as iDriving, iParking, and iShopping with a goal to assist and ease everyday living. The project will deliver an entire solution that includes the handheld positioning device, a smartphone-based software, a PC-based software and scientific publications.