As a platform for community networks, public information spaces that mirror the city metaphor are being developed around the world. The aim of digital cities is to pursue a future information space for everyday urban life, unlike the creation of new businesses which is the current obsession of the Internet. We started the basic research project called “Universal Design of Digital City,” a five year project established in 2000, a part of the Core Research for Evolutional Science and Technology (CREST) run by the Japan Science and Technology Corporation (JST). The objective of this project is to construct digital cities as the infrastructure that encourages the participation of all people, including the disabled and the aged. We will develop basic technologies for the universal design, focusing on ‘sending information,’ ‘receiving information,’ and ‘participation.’ This paper introduces some of various experiments such as crisis management, environmental learning, and shopping street navigation. Digital cities are not imaginary since they correspond to the physical urban spaces in which we live. Basic technologies including perceptual information infrastructure and social agents are being developed for connecting digital and physical cities.