Being the largest Protestant church in a country considered the epicentre of the Protestant faith simply by virtue of having been the motherland of Martin Luther, the Berliner Dom acted as a sort of Protestant equivalent to Saint Peter’s Basilica in the Vatican. Its establishment dates back to the late 15th century, but the building that can be seen today took shape in the 19th century, as testified by the façade’s unmistakable Neo-Renaissance architectural style. Like Germany itself, the Dom went through several 'religious transitions', starting out as Catholic and then converted to Protestantism. It was also a Calvinist church, since in the early 17th century the then prince-elector espoused the Calvinist doctrine, converting his domains along with him following the principle of cuius regio, eius religio, meaning that the state religion of a certain kingdom or princedom should be the same as that of its ruler.