In March 1528 the citizens of Aarau allowed the introduction of Protestantism at the urging of the Bernese. A growth in population during the 16th Century led to taller buildings and denser construction methods.
The acceptance of Protestantism in Aarau in 1528 was driven by pressure from the Bernese.  This coincided with a period of population increase, which resulted in taller buildings and more compact construction methods.