We have developed a digital city for Kyoto, the old capital and cultural center of Japan, as a social information infrastructure for urban everyday life including shopping, business, transportation, education, social welfare and so on. The project was initiated by researchers in NTT and Kyoto University in 1998. In 1999, the Digital City Kyoto Experimentation Forum was launched. The forum includes several universities, local authorities, leading computer companies, local newspaper companies, historical temples, as well as photographers, programmers, students, volunteers and so on. Researchers and designers from overseas have also joined the project. One of the salient features of Digital City Kyoto is that computer scientists from universities and companies have continued to play a leading role in the organization. As a result, Digital City Kyoto is based on the newest technologies including GIS, VR, animation and social agents. The three-layer architecture for digital cities has been proposed: a) the information layer integrates both Web archives and real-time sensory information related to the city, b) the interface layer provides two and three dimensional views of the city, and c) the interaction layer assists social interaction among people who are living/visiting in/at the city. In this paper, the organization and activities of three year experiments, from 1998 to 2001, named Digital City Kyoto, and the technical/social lessons we have learned are described in detail.