Complex sentence: Prior to this, it had become the place where movable type was first used successfully, as it was also the birthplace of the Gutenberg Press "in the 1450's, which was the brainchild of" Johannes Gutenberg.
Split into simpler sentences: Prior to this, it had become the place where movable type was first used successfully. It was also the birthplace of the Gutenberg Press "in the 1450's, which was the brainchild of" Johannes Gutenberg.