This document is a technical report detailing MITRE's Federal AI Sandbox, which serves as a secure environment for federal agencies to experiment with and deploy advanced artificial intelligence solutions tailored to mission needs. The Sandbox is powered by an NVIDIA DGX H100 SuperPOD, featuring 248 NVIDIA H100 GPUs and 9 PB of storage, providing the necessary computational capacity for training and evaluating foundation models. Located in Ashburn, Virginia, the Sandbox supports various applications, including weather modeling, cybersecurity, and healthcare. The report outlines the purpose of the Sandbox, which is to enhance AI research and development, and describes its capabilities, including exaFLOP performance for AI compute and managed AI services. It emphasizes the initiative's alignment with America's AI Action Plan and its role in transforming government efficiency by enabling agencies to leverage supercomputing capabilities for custom AI solutions. The document also invites collaboration from federal sponsors to explore AI's potential in addressing complex governmental challenges.