The Aalen history ties back to the year 150 A.D., when Romans started building a fort house (Römerkastell) here. Thus it is considered as being among the oldest in Germany. It is believed that in the above year, a Roman fortress contained the equestrian unit at the site of present-day Aalen.
The first documented mention of the town was in the year 1136, though there seems be an ambiguity over the precise constructor of the town: whether by the Staufians or by the counts of Oettingen.
Later on, it remained an Imperial City from 1360 to 1803, before being annexed to Württemberg. (Remember, the state Baden-Württemberg consisted of two independent states in the past… Baden (the west) and Württemberg (its eastern part).
Either way, Aaalen witnessed a brutal fire in 1634 and transformed into the seat of an Oberamt from where the district Aalen came into sight in 1938.
The town of Wasseralfingen was amalgamated into Aalen in 1975, which was having the population of one third of Aalen at that time.