There are many witch towers in Germany, locally called ‘hexenturm’. Originally they served as prisons but when the Christian Church began its campaign against 'witchcraft' they become known, and still are today, as 'witch towers'.

This one is in Landsberg am Lech (Upper Bavaria):
http://www.itcwebdesigns.com/tour_germany/hexent1.jpg

This one is in Neben der Liebfrauenkirche:
http://photos.imageevent.com/ralf/germany/guenzburg/icons/PIC13158.jpg

This one is in Hessen:
http://i1.trekearth.com/photos/9393/witchtower_s_.jpg

This one is in Gelnhausen:
http://de.wikipedia.org/wiki/Bild:Gelnhausen_Hexenturm.jpg

This one is in Bergfried:
http://www.nassau-info.de/idstein/hexenturm1.jpg

This one is in Forschungsstadt:
http://www.juelich.de/bilder/hexenturm-gr.jpg

This one is in Mellingen:
http://www.mellingen.ch/Bilder/Fotogalerie/Hexenturm2_gross.jpg