Thracian sanctuary of the Three Nymphs
In Greek mythology, the beautiful and seductive Nymphs were the patrons of the springs and all nature. The number of descendants of Oceans and Tethys exceeded 3000. The poet Hesiod (8-7 century BC) claims that no one is able to list their names. Some of them were guardians of salty waters – they were called Oceanids. Others watched over the sweet waters - they were called "Naiady". It was believed that the streams guarded by them had healing powers, and they often donated eternal youth and immortality.
The legend tells that three of these Nymphs were guardians of the healing springs near the ancient city of Aquae Calidae – in translation: hot water. The maidens sinned, they have not kept the purity, and the angry gods petrified them.
Already in the first millennium BC, the sanctuary of the Three Nymphs to the hot mineral spring was a sacred place for the Thracians. For centuries, people from different nations and countries of the then-world were attracted by its extraordinary power.
Construction of the Roman Baths
In the middle of the 1st century BC, the Roman Empire annexed the Odrysian Kingdom and created the province of Thrace. Public baths (thermal baths) occupied an essential part in the philosophical maxim of Roman citizens for "Healthy spirit in a healthy body". Besides for hygienic and curative purposes, the baths were also used for holding sports games. Visitors indulged cultural entertainment, poetry, music, and even political debates.
During the reign of Emperor Trajan (98-117), the construction of public baths and roads were the main state policy of the Empire, in the creation of urban centres in the new provinces. He himself is a great fan of the mineral springs, which plays an important role in the selection of the first autonomous centres in the province of Thrace. Thus, the old Thracian settlements, known in ancient times with its mineral springs, got an urban status: Serdica (today’s Sofia), Pautalia (today’s Kyustendil), Nicopolis ad Nestum (today’s Gotse Delchev).
In the II century, in the area of the mineral springs was build a road station called Aquae Calidae, and the glory of this area continued to come from the sanctuary of the three Nymphs.
Later, another Roman emperor, Septimius Severus (193-211), organized special celebrations and sports games called "Severa Nymphaea".
The historian Jordanes (6th century) mentions Aquae Calidae, describing the Gothic attacks against cities along the Western Black Sea coast. Aquae Calidae suffered severely injured by the attack, but the warm mineral baths were preserved. Moreover, the healing properties of the mineral springs seem to pacify the Gothic tribes, and as Jordanes wrote: "Here they stayed, as they say, for many days enjoying the warm baths. Their hot waters gush through the depths of its spring, and among the countless hot baths all over the world, they are in every respect excellent and most useful for treating the sick. "
Construction of the fortress walls
In the sixth century, the attacks of barbarian tribes over the provinces of the Eastern Roman Empire increased. This forced the Emperor Justinian I (527-565) to undertake a colossal construction campaign to protect the population. For the first time, the city of Aquae Calidae and the baths were protected by a fortress wall. The chronicle Procopius of Caesarea says: “However, in this place that had remained uncorrupted in old times, the earlier Emperors looked with disdain if there were many Barbarian tribes in the neighbourhood and visited by sick people who were relieved of their pain at the risk of their lives. But now Emperor Justinian has encircled him with walls and has made healing them safely.”
The establishment of the Bulgarian State
The healing springs of Aquae Calidae play an important role in the creation of the Bulgarian state. In the spring of 680, the Byzantine Emperor Constantine IV (688-685) organized a battle against the Bulgars of Khan Asparuh who were fortified in Ongal. Before the decisive battle, the Emperor had commanded his generals, and he himself retired under the pretext that it would treat gout. Since ancient times, the mineral waters of Aquae Calidae have been used to treat this disease, and it is supposed that looking for relief for his physical suffering, Constantine IV directed to them.
Whatever the real motives for this Emperor's action, namely the Mineral Baths are part of the historical events that allow Khan Asparuh to defeat the Romans and together with his people permanently settled south of the Danube River.
After the establishment of the Bulgarian state, the city of the hot springs is now called Therma or Thermopolis. It turns out to be the centre of the important historical events during the time of the Bulgarian Khan Tervel (700 / 701-718 / 721). In 708, not far from this city, there was one of the most fateful battles between Bulgaria and Byzantium. The army of Emperor Justinian II Rhinotmetos (685-695 and 705-711) was defeated by the Bulgarians and thus, affirming the territorial expansion of the Bulgarian state to the south of the Balkan Mountains.
In 1204, the Knights of the Fourth Crusade conquered Constantinople and created the Latin Empire. In the ensuing war between Latins and Bulgarians, Emperor Baldwin I Flanders (1204-1205) was captured by the army of Tsar Kaloyan (1197-1207). The next Latin Emperor Henri of Flanders (1205-1216), Baldwin's brother, took a punitive march against the Bulgarian cities south of the Balkan Mountains. Many cities, such as Adrianople (today’s Edirne), Beroe (today’s Stara Zagora) and others, had been captured and plundered. The Knights conquered the city of Terme, called from them “La Ferme”. One of the chroniclers of these events, the Marshal of Champagne and of Romania - Geoffroy of Villehardouin (1150-1212 / 1218), says: "... they departed from Ferme which was beautiful and well located; there sprang warm waters - the best in the world; and the Emperor commanded them to destroy and burn it, and took with him a great prey of animals and other riches. "
For a long time after the burning of Terme/Thermopolis, the mineral baths remained in ruins. Under the rule of Sultan Suleiman I the Magnificent (1520-1566), the building of a new bathroom (kapladza hammam) was built on the semi-destroyed pools. As a gratitude for the healed gout, the sultan issued a screed that richly endowed the area of the mineral springs. This underlies the future economic development of the surrounding settlements.