We present enabling capabilities and key results realized by the development and implementation of 300-mm full-factory simulation tools supporting Intel's 90-nm high-volume manufacturing and 65-nm technology development factories. We discuss key attributes of these simulators which are being utilized for strategic fab capacity planning, automation systems designs, and tactical manufacturing execution and decision support for continuous improvement. These simulators capture the dynamic behaviors of hundreds of production tools with thousands of production and engineering lots and integrate automated material handling systems (AMHS) behaviors in these production simulations. The paper discusses specific topical areas where these tools have found widespread use and emphasizes the importance of periodic model validation and calibration to the real factory.