Hisar means „fortress“ in Arabic. Today, this lovely town has become a genuine fortress of health and beauty. It is located on the South flanks of Sredna Gora, surrounded by picturesque parks and gardens. The resort area includes 22 springs located in a small region that have various physical and chemical characteristics and hold a temperature between 41 and 52 °С. This is unique not only in Bulgaria, but also in the world.
The water is low in mineralization, containing hydrocarbonate, sulphate, and sodium. It also has a high alkaline reaction and a low solidity; it is bright, colorless, and tasty. Here you can see the remains of the biggest Roman bath, discovered in 1935. Archaeologists date its construction as far back as the 4th century. There were rooms for hot and cold baths, a place for relaxation and two pools. In other special rooms, the priests were conducting healing procedures after the baths, massages and covering with fragrant oils. The bath also had a nympheum, a sanctuary consecrated to the nymphs, worshiped as deities of springs and healing water. An interesting bit of trivia, Emperor Diocletian, who the town was named after, introduced the first bath entrance fees in the world. The mineral waters of the resort are used for effective treatment of kidney, gall, urological, gastrointestinal, liver and motor diseases. Very good results are obtained in patients with kidney stones, kidney microlithiasis and post-operative conditions, as well as obesity, and many others.