Baden is a municipality in the Swiss canton of Aargau, on the west bank of the river Limmat, located in the Limmat Valley (German: Limmattal), northwest of Zürich. It is the seat of the district of Baden. The name refers to the mineral hot springs, which were known at least as far back as the Roman era.
Its population in 2010 was over 18,000.
Baden was known to the Romans as Aquae Helveticae. In 1040 the town is first mentioned as Baden.
Aquae Helveticae was mentioned by Roman historian Tacitus. At that time it was a Roman Vicus to the north of the Baden gorge on the Haselfeld. On the left bank of the Limmat bend there was a pool complex, which was fed by the water from a system of springs. The Vicus was founded to support the establishment of the legionary camp at Vindonissa. Both the spa quarter and the residential and commercial district grew to a respectable size in the first half of the first Century AD. The town suffered a setback in 69 AD as members of the XXI Legion burned the wooden buildings of the vicus during the Year of the Four Emperors. The town was rebuilt in stone. When the legion camp at Vindonissa closed in 101 AD, the town shrank again slightly. Although the prosperity of the local spas diminished, the town survived on trade. The pottery workshop of Reginus and the bronze works of Gemellianus flourished in the second half of the 2nd Century. The multiple Alemanni invasions in the different ideas about the middle of the 3rd Century brought an end to settlement at Haselfeld. However, the construction of a fortification to protect the pools, along with a large number of coins from the 4th century which are stamped with references to the hot springs show that the spa area remained settled in late antiquity and was frequented.
The main axis of the Vicus was the street which came from Vindonissa. On both sides of this road, which ran parallel to the edge of the steep slope, there were residential and commercial buildings. The road was flanked by porticos, behind which were the retail stores. Behind the commercial buildings were the living quarters, adjoining farms, work spaces and outbuildings. In the center of the settlement were some villa-like buildings. Modernly, the remains of three thermal bathing pools have been discovered.
Stein Castle, formerly a stronghold of the Habsburgs, was destroyed in 1415 and again in 1712. In 1415, Baden (along with Aargau) was conquered by the Eight Swiss Confederates, whose bailiff inhabited the other castle, on the right bank of the Limmat, which defends the ancient bridge across the river. As the conquest of the Aargau was the first made by the Confederates, their delegates (or the federal diet) naturally met at Baden, from 1426 to about 1712, to settle matters relating to these subject lands, so that during that period Baden was effectively the capital of Switzerland. The diet sat in the beautifully carved diet hall in the town-hall or Rathaus, which can be visited. In 1714 the Treaty of Baden was signed, which put to an end to the war between France and the Holy Roman Empire, and thus completed the treaty of Utrecht (1713). Baden was the capital of the canton of Baden, from 1798 until 1803, when the canton of Aargau was created.
Having attained popularity as a Spa and 'Kur-Ort' (Cure resort) during the 15th and 16th centuries, Baden remained popular and was later frequented by an array of prominent people including Johann Wolfgang Goethe, Friedrich Nietzsche, Thomas Mann, and Hermann Hesse, who was to become a particular devotee, visiting the town annually over a period of almost 30 years.