Read the source given below and answer the question that follows:

In 1517, the religious reformer Martin Luther wrote Ninety-Five Theses criticising many of the practices and rituals of the Roman Catholic Church. A printed copy of this was posted on a church door in Wittenberg. It challenged the Church to debate his ideas. Luther's writings were immediately reproduced in vast numbers and read widely. It led to a division within the Church and the Protestant Reformation's beginning. Luther's translation of the New Testament sold 5000 copies within a few weeks, and a second edition appeared within three months. Deeply grateful to print, Luther said, “Printing is the ultimate gift of God and the greatest one”. Several scholars think that print brought about a new intellectual atmosphere and helped spread the new ideas that led to the Reformation.

A printed copy of these was posted on a ____ in Wittenberg.