The Manningaburg castle in Pewsum dates back to the year 1458 and was originally - as the name suggests - the headquarters of the chief family Manninga. However, in 1565 the castle was sold from Chief Haiko Manninga to Count Edzard II Cirksenas. Unlike most castles in Ostfriesland, Manningaburg is open to the public and houses a museum dedicated to the chief and castle history. In the ceremonial hall of the castle, you can get married in a civil ceremony.
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.