As a platform for community networks, information spaces using the city metaphor are being developed in worldwide. This paper compares the trials of digital cities. Four digital cities, those of America Online, Amsterdam, Helsinki and Kyoto, are introduced. It is interesting to note that each digital city has a different goal: to explore a vertical market, a public communication space, a next generation metropolitan network, and a social information infrastructure for the 21st century, respectively. Their different services, system architectures, and organizations result from the different goals. Digital cities will change together with the advance of computer and network technologies. No digital city can remain at its current status. This paper reviews those digital cities to have a better understanding of their current status and future.