Gravensteen

Gravensteen Castle (Dutch: Gravensteen, literally: "castle of the count") is a medieval castle in Ghent, Belgium. It is the only medieval castle in Flanders, defensive system of which has remained virtually untouched to this day.

This is a file from www.rowing-vvr.be

The present castle was built in 1180 by Count Philip of Alsace (was Count of Flanders from 1168 to 1191). The counts of Flanders had built castles in the principal cities of the county. Because they had to maintain law and order, they continuously had to move from one city to the other. Therefore, they disposed of a castle in most cities where they wanted to stay for a few months. The castle of Ghent is the only one which survived the centuries more or less intact.

Château de Sarzay

The Château de Sarzay is a 14th century castle in the village of Sarzay in the Indre département of France. Château de Sarzay is one of the chateaus of the southern Loire Valley, which although close to a tributary of the Indre, but already adjacent to the foothills of the Massif Central. Like many buildings of this type in the Auvergne and Limousin, Sarzay had a rectangular form, flanked by 25-meter cylindrical high towers. The château was protected by two outer walls, and 38 towers. In the first period there was also a moat with three drawbridges and a 4-acre pond.

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Author: Manfred Heyde, License 

Burg Steen

Burg Steen, also known as Het Steen, (Dutch: Steen, literally: "Stone") is a part of the medieval fortress on the right bank of the Scheldt River in the old city centre of Antwerp, Belgium.

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The castle was built between 1200 and 1225 after the Viking incursions in the early Middle Ages.  It was originally called the Antwerp Burcht (citadel). At that time, it was the first large stone building in Antwerp. Unfortunately, the building, preserved to this day, is only a small part of the old fortress. The old fortress covered an area in several times larger. Inside that castle were important institutions such as the Vierschaar (the former courthouse), St. Walburgis Church, the Fish Market, warehousing and storage facilities and a number of other buildings. The entire complex was surrounded by a massive defensive wall. The fortress made it possible to control the access to the Scheldt River and to guard the entrance to the city from the direction of the Western Scheldt.

Löwenburg

Löwenburg (German: Löwenburg, literally: "Lion Castle") is one of the most beautiful castles in the world. The castle is located in the German town of Kassel, in the Wilhelmshöhe Mountain Park, on the Bavaria mountain, altitude 92 meters above sea level.

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From a distance it appears to the visitor as a romantic Gothic castle from the Middle Ages.  However, it was built between 1793 and 1801 at the time when the era of construction of the formidable and fortified castles in Germany was ended a few centuries ago. William IX, Landgrave of Hesse-Kassel, inspired by the medieval romance, commissioned the architect Heinrich Christoph Jussow build the castle, which can be compared with the English medieval palaces.

Kalmar Castle

Kalmar Castle (Swedish: Kalmar slott) is one of the most significant creations of Northern European fortification art of the Renaissance. The castle is located in the small town of Kalmar in the province Småland on the southern coast of Sweden.

This is a file from geeson.deviantart.com, Author: geeson 

The area around Kalmar has been inhabited since ancient times. At the diggings have been found traces of ancient burials of the stone age. However, the first mentions of this place belong to the 11th century. According to a medieval folk tale, the Norwegian patron Saint Olav had moved his ships to Kalmar strait. There are very few written sources of this event, but archaeologists found a stone, in which there is mention of this strait.