This article explores the design and construction of a geo-spatial Internet web service application from the host web site perspective and from the perspective of an application using the web service. The TerraService.NET web service was added to the popular TerraServer database and web site with no major structural changes to the database. The article discusses web service design, implementation, and deployment concepts and design guidelines. Web services enable applications that aggregate and interact with information and resources from Internet-scale distributed servers. The article presents the design of two USDA applications that interoperate with database and web service resources in Fort Collins Colorado and the TerraService web service located in Tukwila Washington.