Mszczonów Town is more that 630 years old and was granted civic rights by Mazovian Prince Ziemowit III in 1377. The locality has mentioned the first time occasionally more than 760 years ago as already existing village being the place of the issue of a document which was not directly associated with this place. Therefore we could make a hypothesis that Mszczonów was then the property of a prince with a small mansion used as the stopping place by the princes hunting in surrounding wide – spread forests.
Mszczonów was situated on the trade route leading from the north to south. The famous Amber Route crossed this area many years ago. The presence of the local church is documented since 1324. This church had the status of a parish church before the foundation of the town.
In 15th century Mszczonów became the principal town of a small Mszczonowski Poviat with surface area of 405 km2.
In 16th century the town became the property of Radziejowski family being the owners of adjacent property Radziejowice i.e. first in the form of life leasehold and finally as their succession. The owners mainly took care of their own interests and reduced development potential of the town by restrictive fiscal policy.