The warm, graceful charm and sedate pace of Kos Town is experienced at its best in this lovely cobblestone square, immediately south of the castle. Sitting in a cafe here, you can pay your respects to Hippocrates' plane tree. Hippocrates himself is said to have taught his pupils in its shade. The ancient sarcophagus beneath it was converted into a fountain by the Ottomans, while the 18th-century Mosque of Gazi Hassan Pasha, now sadly in disrepair, stands opposite.