In addition to being one of the most recognizable monuments at the site, the Roman Bath at Isthmia in Greece continues to yield surprising discoveries. Excavations in the
1960s through the 1980s revealed not only the 2nd c. CE structure but also parts of an earlier Greek-period pool of impressive dimensions—a fitting monument at a
Sanctuary of Poseidon. Most recently, a re-investigation of the excavated material and associated documentation has revealed the presence of a third structure that fits in time between the other two. This presentation discusses these buildings by focusing on the discovery in this location of tegula mammata—a peculiar type of tile used in heating systems in Roman-style baths prior to the adoption of the more common tubulus. These artifacts provide evidence for changes both to Roman building practices of the 1st century CE and to the athletic sanctuary as Romans from the re-founded colony of Corinth returned to Isthmia with their own unique needs and expectations.