The great baths were constructed with huge stone blocks without the use of cement, and consisted of various closed or open sections linked together. There are deep niches in the inner section of the bath, library, gymnasium and other closed or open locations. The complex, which was constructed in the 2nd century BCE, constitutes a good example of vault type architecture. The complex is now an archaeological museum.
Today's Antique Pool was shaped by the earthquake which happened in the 7th century AD. The marble portico with Ionic arrangement fell into the spring during that earthquake. The water in the thermal pool is 36-57 °C, pH value is 5.8 and radon value is 1480 pCi/l. The spa water contains bicarbonate, sulphate and carbon dioxide, as well as iron and radioactive combination. The water in this spring is suitable for taking showers and drinking cures, 2430 MG/liter melt metal value.