Iburg is a ruined hill castle in Westphalia. It was build around the 8th century, dating back to the time of Charlemagne and his war with the Saxons. Today it is a popular day-trip destination and the tower, named after Charlemagne (Kaiser Karl Turm), can be climbed for beautiful views.
It is likely that the castle was originally erected by Saxons as a fortified stronghold but once conquered Charlemagne build a chapel within its confines to honour St.Peter, which he eventually gifted to the Arch-Diocese of Paderborn. From 1134 a monastery briefly used the castle before the Bishop of Paderborn fortified it to become a stronger military fortress in the late 12th century. The Iburg never saw much action, however, and slipped from importance until the 15th century, when Otto of Braunschweig destroyed it. The castle was not restored and the close-by city of Bad Driburg inherited the holdings.
First archeological surveys were undertaken on 1900 and gradually the ruins where freed and restored to serve as tourist attraction.
References:House of the Blackheads (Melngalvju nams) is a building situated in the old town of Riga. The original building was erected during the first third of the 14th century for the Brotherhood of Blackheads, a guild for unmarried German merchants in Riga. Major works were done in the years 1580 and 1886, adding most of the ornaments.
The structure was bombed to a ruin by the Germans June 28, 1941 and the remains demolished by the Soviets in 1948. The current reconstruction was erected from 1995 to 1999. Today the House of Blackheads serves as a museum and sometimes concert hall.