The Eresian Baths were a large public structure centrally located in the historical Inner City of Epichirisi, standing near to the Remmos. Cool water piped from the hills entered the a great pool at the center or one of a dozen smaller pools, including several heated ones. An evolution of the Opulensi bathhouse, the Eresian Baths were the prototypical ondeson - a complex containing as core features swimming and bathing pools, facilities for sports and fitness, and social gathering places. Cool water was piped via aqueduct from the hills to the east of the city to feed its many pools and fountains.
The Eresian Baths contained a large coldwater swimming pool, or nadio, at its centre, and the entirety of the structure was built around it. The nadio pool itself was lined in smooth granite, and was built with a gravity drainage system, allowing the pool to be emptied and cleaned overnight. The walls of the nadio chamber were painted with varied and colourful frescoes of ships under sail, sea birds, coral reefs, leaping dolphins and cresting pods of wails, and other scenes of maritime life. The roof directly overhead was open to the sky, lighting the interior. Smaller bathing pools - both hot and cold - could be found in chambers radiating off of the nadio, a set of these baths existing for each gender. Separate undressing rooms were provided for men and women - and for a small fee, bathers could have their belongings held in a storeroom by staff, to be retrieved on departure. Admission to the pool and baths cost only a single low-denomination coin, so that the facilities should be patronized by the common people.
The complex featured an open promenade near its entrance, a frequent haunt for the people of the city, who would come to talk, socialize, and shop at the various vendors. In the outer halls to either side of the nadio and baths were two large courts with floors of varnished wood, built for playing the game of oin, a handball sport popular among young men and women. The ondeson was surrounded by well-tended gardens and parks with walking trails and fountains. A long straight track of for running was located on site, with an adjacent field for various throwing sports.