During the reign of Emperor Claudius (41 to 54 AD), the region around Baden became part of the Roman province of Pannonia. The Danube served as its northern border.
The Romans forced the Celtic population to leave their mountain villages and move to the newly established settlements in the plains. That was also true in Baden. The new town was named Aquae, which means waters, baths. However, Baden was not only a health resort, it was also an important postal station. This was the first place tired horses could be exchanged for fresh ones on the journey from Vienna southwards. The most important sulfuric spring in Baden is in the Spa Park (Kurpark) and is known as Source Spring (Ursprungsquelle), or Roman Spring.

There was once a Roman hot springs bath here. It was 53 m long and 8 to 10 m wide and was equipped with pleasant under-floor heating.
Baden served primarily as a military bath for soldiers from Carnuntum and Vienna (Vindobona). Spa guests had altars built to various gods as a sign of gratitude for successful treatments. They were set up near the Roman Spring. Two of them have survived to this day: One is dedicated to the goddess of health (Salus), the other to the fairies who lived in the sulfuric springs, mythical beings the Romans called nymphs.
In other words Baden has been a well-known health resort for nearly 2000 years!