Enterprise GIS is often understood to be only a marketing term for big companies and public institutions to purchase more software and services. Enterprise GIS can be built with FOSS4G (Free and Open Source Software for Geospatial). In this talk, I will cover basics of enterprise architecture and real world examples of how to use FOSS4G to build sustainable and affordable solutions for enterprises. Enterprise GIS is an organisation-wide collection of interoperable GIS softwares to manage and process geospatial information. Enterprise GIS will follow basic principles of enterprise architecture. Enterprise GIS architecture is based on three layers: User Interface, Application Server and Data Storage layers. In this talk, I will give best practices to define and design Enterprise GIS architecture. This presentation is targeted to ICT and GIS experts to better understand how to build Enterprise GIS with FOSS4G. After the presentation, you understand how to start the design and implementation of Enterprise GIS. You also have basic knowledge on how to use FOSS4G to build Enterprise GIS.