This paper discusses the design and performance of a proxy-cache designed to make Internet information systems scale better. A hierarchical arrangement of caches mirroring the topology of a wide-area internetwork can help distribute load away from server hot spots raised by globally popular information objects, reduce access latency, and protect the network from erroneous clients. We present performance figures indicating that the cache significantly outperforms other popular Internet cache implementations at highly concurrent load and that indicate the effect of hierarachy on cache access latency. We also summarize the results of experiments comparing TTL-based consistency with an approach that fans out invalidations through the cache hierarchy. Finally, we present experiences derived from fitting the cache into the increasingly complex and operational work of Internet information systems, including issues related to security, transparency to cache-unaware clients, and the role of file systems in support of ubiquitous wide-area information systems.