Viewpoints are reflections of software systems from multiple perspectives. A number of consistency conditions apply to viewpoints and developers require a tool for each type of viewpoint. These tools need to support consistency management. Inter-viewpoint consistency can only be checked when tools are integrated into a viewpoint development environment. We briefly outline the functionality developers require from these environments. We discuss the suitability of abstract syntax graphs as a common viewpoint representation scheme. The main purpose of the paper is to present an object-oriented architecture for viewpoint-based environments. The architecture benefits from the integration of object database management systems and object request brokers.