Aquae Iasae: A Roman Healing Sanctuary in Croatia
Site at a Glance
- Rating
- 4.6
- Popularity
- Low
- Country
- Croatia
- Primary era
- Classical
- Eras represented
- Classical
- Civilizations
- Illyrian, Roman
- Site type
- City
On this page11 sections
History
Aquae Iasae was a Roman healing sanctuary and thermal settlement at Varaždinske Toplice in Croatia, developed around hot, sulfur-rich springs from the first to the fourth century. Its name refers to the Jasi, an Illyrian tribal population associated with the region before Roman rule, and means approximately “waters of the Jasi.” The settlement belonged administratively to the Poetovian area of Pannonia Superior, a Roman imperial province in the central Danube region.
The precise date when the Roman settlement was constructed is unknown, although its development is generally placed during the Flavian dynasty. The wider area had already been inhabited since the Paleolithic period. Aquae Iasae stood on the route between Poetovio, the Roman settlement at present-day Ptuj in Slovenia, and Iovia-Botivo, present-day Ludbreg. Its position near the Bednja River and the Drava River supported its development as a medical, religious, ceremonial, cultural, commercial, and economic center.
Development around the thermal springs
The settlement grew around naturally hot mineral water, which emerged at approximately 58°C and was especially rich in sulfur, calcium, and sodium. Medicinal mud was also associated with the area. The healing baths attracted local worshippers and visitors, including soldiers, while the surrounding settlement provided space for residential, craft, commercial, and fair-related activities.
The public center occupied the highest terrace of the hill. Residential areas extended down the terraces toward its foot, while craft, commercial, and fair-related facilities stood at the base. During the first century, the sanctuary was devoted entirely to nymphs, divine female beings associated with springs and other natural places. In the second century, it expanded into a forum-centered sanctuary that incorporated additional cults.
Religious life and later destruction
Worshippers left stone inscriptions expressing thanks for healing to Minerva, Diana, Apollo, Aesculapius, and the nymphs who protected the springs. Aesculapius was the Roman god of medicine, while Hygieia was associated with health and Telesphorus with recovery. Mithras, a deity venerated in Roman mystery cults by some soldiers and other initiated groups, was also worshipped at Aquae Iasae. A relief connects Aesculapius, Hygieia, and Telesphorus in the context of healing.
The settlement was devastated at the end of the third century during a Gothic incursion. Emperor Constantine I restored the thermal complex at the beginning of the fourth century. A stone inscription associated with Constantine states that the place, previously consumed by fire, was restored with its porticoes and ornaments to its former appearance. The plaque was discovered in the eighteenth century.
Aquae Iasae was destroyed again during fourth-century invasions associated with the Migration Period and was then abandoned. The surviving complex preserves remains from the first through the fourth century, with the most substantial remains belonging to Constantine’s restoration.
Archaeological investigation and preservation
The Zagreb Archaeological Museum began systematic research at Aquae Iasae in 1953 under Marcel Gorenc. Approximately 6,000 square metres have been investigated, although modern buildings occupy part of the settlement and prevent its complete excavation. Travertine, a form of limestone deposited by mineral-rich spring water, accumulated over the complex and, together with the local soil conditions around the springs, helped protect the Roman masonry and other remains. Aquae Iasae is regarded as one of the best-preserved Roman archaeological sites in Croatia.
Remains
The excavated complex covers about 6,000 square metres in the present spa park. Its layout brought together public baths, pools, a large hall, a forum with porticoes around the principal spring, and a northern group of temples. The thermal spring formed the physical and religious focus of the settlement, while channels connected its water installations with the bathing buildings.
Bathing buildings and basilica
Early baths
The earliest known baths date from the first century and occupied the southwestern part of the site. Covering approximately 200 square metres, they contained several rectangular rooms without a heating system and a pool that probably used water from the thermal spring. Inscriptions show that soldiers used these early bathing facilities.
Later bathing complex
New baths were built during the reigns of Hadrian and Antoninus Pius. Their remains are poorly preserved, but the complex continued to be renewed and enlarged while retaining its public, religious, and bathing functions. The public baths included bathing buildings, pools, and the thermal basilica, with fourth-century walls, frescoes, heating installations, and plastered floors surviving particularly well.
Thermal basilica
The thermal basilica, or basilica thermarum, was a rectangular hall measuring approximately 22.5 by 14.5 metres. Its roughly dressed and broken-stone walls survive to a height of about 2.8 metres. Doorways on the western and northern sides were later blocked, while the southern side had a monumental entrance with a stone threshold and steps preceded by a vestibule.
A heating system was installed inside the basilica. The floor was red and polished, and a large semicircular exedra, a recessed curved space, occupied the northern end. Its ends terminated in pilasters. The exedra was richly decorated, although only part of its ornamentation survives. A fragment showing a bearded, haloed man, interpreted as a saint, belongs to a later period.
Forum and spring installations
The forum was built around the principal natural thermal spring and was lined with porticoes, covered walkways supported by columns. A nymphaeum, a decorative structure associated with a spring, was added during the second-century expansion of the sanctuary.
Recent investigations uncovered a Roman basin supplied directly by the spring. It measures approximately 8 by 13.5 metres and is 2.6 metres deep. Large stone blocks enclosed the spring, while channels carried water onward to the baths. A comparable basin is known at Aquae Sulis in present-day Bath, England.
Temples and votive remains
Three temples stood north of the bathing buildings and basilica, separated from them by the thermal spring. They are associated with Jupiter, Juno, and Minerva, although their identification as a Capitolium, a temple complex for these three principal deities of the Roman state cult, remains uncertain. A third room was probably dedicated to Jupiter, but that interpretation is not confirmed.
A statue of Minerva and its pedestal were found at the entrance to her temple in 1967. Made in Poetovio during the mid-second century, the statue shows the goddess wearing a legionary helmet and carrying a spear and shield. A councilor commissioned it as a votive offering for healing. A Minerva inscription was found with the statue, while a separate inscription was dedicated to Juno.
The complex has also yielded parts of swords, shields, knives, and razors. Imperial coins were thrown into a pool as good-luck offerings, and numerous representations of healing nymphs were found. A well-preserved second-century pavement, composed mostly of marble slabs, adds to the surviving evidence for the sanctuary’s public and religious spaces. Together with the pools, temple elements, inscriptions, sculptures, frescoes, and water-management installations, these remains preserve the organization of a Roman settlement centered on thermal healing.
