The U.S. Department of Energy has spent the past decade preparing for the challenges of building an exascale computer in the 2021–2022 timeframe. This talk describes Oak Ridge National Laboratory’s road to exascale and the challenges that face exascale computers. It will describe OLCF’s shift two generations ago to accelerated node computing and the ability of Summit to handle AI and data analytics in addition to traditional modeling and simulation. The talk shows how Frontier continues the accelerated node architecture and compares its capabilities to Titan and Summit. The talk concludes by describing how Frontier addresses the original exascale challenges.