The old church (Oude Kerk) stands in the heart of the red-light district as if it was watching all the carnival underneath its feet. However, it is the most important monument in Amsterdam and has been playing the role of the cathedral since it was built in the early 13th century. The church was originally dedicated to Saint Nicholas, the sailor's guardian saint, but after the religious revolution, the church was accepted by Protestants, and now only in some humble corners can the traces of the old religion be found.