This paper describes a large-scale collaborative virtual environment architecture that has the capability of scaling across multiple geographically dispersed resources. The architecture consists of distributed mobile agents working cooperatively in supporting and managing the virtual environments. The mobile agents? tasks include managing persistency and consistency of the virtual worlds, maintaining reliability and efficiency of user interactions, ensuring security and integrity of data and systems, and so on. The mobile agents are autonomous and has the ability of migrating among hosts to maximize resource utilizations. Grid technologies and concepts are introduced into the architecture. These improvements allow the mobile agents to execute and communicate securely in multiple administrative domains. Grid-based scheduling components and polices are integrated to provide intelligent resource optimizations. Furthermore, a better load-balancing can be achieved by utilizing additional or more accurate information like data-user proximity and hosts? workload invariance etc. The result will be a more scalable and robust mobile agent architecture.