|Summary:||Water clock and small annex; southeast of the Sanctuary of Amphiaraios, across the stream and east of the Temple of Amphiaraios.|
Entrance at north corner of nearly square stone structure with landings and stairs leading down to the plug and exit channels of a central square basin. On the southwest an attached room of uncertain use.
Klepsydrai ("water thieves") were used to time legal arguments and other contests. The deep basin was filled and a bronze stopper at its base opened to allow a controlled flow of water to escape. A float carrying a vertical pole with time measurements would slowly sink as the water subsided, and its calibrated disappearance gave an estimate of time. The clock would have been visible from parts of the theater and from the dramatic area in front of the Temple of Amphiaraios.