The Microsoft TerraServer stores aerial and satellite images of the earth in a SQL Server Database served to the public via the Internet. It is the world’s largest atlas, combining five terabytes of image data from the United States Geodetic Survey, Sovinformsputnik, and Encarta Virtual Globe™. Internet browsers provide intuitive spatial and gazetteer interfaces to the data. The TerraServer demonstrates the scalability of Microsoft’s Windows NT Server and SQL Server running on Compaq AlphaServer 8400 and StorageWorks™ hardware. The TerraServer is also an E-Commerce application. Users can buy the right to use the imagery using Microsoft Site Servers managed by the USGS and Aerial Images. This paper describes the TerraServer’s design and implementation.