Wartburg Castle. Located between Frankfurt and Berlin at Eisenach, and perched on a hill, this is where Martin Luther stayed from May 1521 until March 1522. The large tower in the middle is the Castle Keep, and was finished in 1859. Its base partially includes the foundation of its medieval predecessor. One of the castle's landmarks-the four-meter tall Latin cross-is located at the top of the keep and is visible from afar. www.wartburg-eisenach.de/frame_sn.htm