Malbork Castle

Also know as Marienburg, this castle was built by the Teutonic Knights in the late 13th century.  It also served at times as part of the Prussian royal residences.

More than half of the castle was destroyed during World War II.

The exterior of the east window of the upper chapel was decorated by the first examples of exterior mosaics by Salviati in what was then still part of Germany. This was restoration work done in 1869-70 to previous mosaics (also Venetian, from the 14th century) adorning the niche of the giant (8 meters) statue of the Virgin Mary. Unfortunately, these mosaics also did not survive the wartime bombings.

A pre-World War II postcard showing the statue and mosaics still intact on the chapel.

The mosaics formed a background of gold with blue stars.

Malbork Chapel with the empty space that previously featured the mosaics and the Virgin

In 2008, an advertisement for a local religious organization showed what the chapel used to look like.

Sources:
The Architect and Contracted Reporter: A Weekly Illustrated Journal of Art, Civil Engineering and Building. "Mosaics in Germany." Vol. 5, April 8, 1871. 182.
Castles and Palaces of the World
Wikipedia
Malbork
pBase gallery
forum Marienburg.pl
Akpool.de
Stadtapartment
Mysteries and Curiosities of Malbork Castle