Castle of Coca

Castle of Coca or Castillo de Coca is considered to be one of the best castles in Spain. The castle is located in the city of Coca (Roman "Cauca"; birthplace of Roman Emperor Theodosius) in the province of Segovia, which lies in flat and wooded lands of the center of Spain, in the autonomous community of Castile and Leon. 

This is a file from the Wikimedia Commons, Author: Ignacio Cobos Rey, License

It is an excellent example of the Gothic and Mudéjar styles. It's made up of two square baileys separated by a passageway. Both show polygonal towers at the corners. The castle is surrounded by a fortress double wall of width of 2.5 meters with lots of corridors and doors, as well as a deep dry moat. It is considered to be the highest example of brick military architecture with Mudejar filigree work.

Muiden Castle

Muiden Castle, also known as Muiderslot, is one of the better known castles in the Netherlands. It is located at the mouth of the river Vecht, some 15 kilometers southeast of Amsterdam, in Muiden, where it flows into what used to be the Zuiderzee. It is a relatively small castle, measuring 32 by 35 metres with brick walls well over 1.5 metres thick. A large moat surrounded the castle.

Author    Edi Weissmann from Amsterdam, Netherlands, License

Name: Muiden Castle

Country: Netherlands
Province: North Holland

City: Muiden

Type: Water castle

Material: Brick 
Start of construction:1370

Condition:  opened to the public
Website: www.muiderslot.nl

The history of the Muiderslot begins in 1280, when Count Floris V of Holland built a stone castle on this site to control the estuary of the river Vecht into the former Zuidersea. The River Vecht was the trade route to Utrecht, one of the most important trade towns of that age. The castle was used to collect a tribute on the traders. In 1296 Floris was abducted by rebelling noblemen and was held prisoner in Muiden Castle. They fled under the threat of a siege in the direction of Utrecht, taking Floris with them. During their escape they murdered Floris with their swords. Taking into account the death of Count Floris, and the fact that in the castle was not his immediate successor (son of Count Floris was in England), the castle was besieged by Willem van Mechelen, bishop of Utrecht. After seizing the castle he destroyed it.

Carcassonne

Carcassonne is a fortified French town in the Aude department, of which it is the prefecture, in the former province of Languedoc. It is divided into the fortified Cité de Carcassonne and the more expansive lower city, the ville basse. Carcassone was founded by the Visigoths in the fifth century, though the Romans had fortified the settlement earlier.

Author    Jondu11, License

First signs of settlement in this region have been dated to about 3500 BC, but the hill site of Carsac – a Celtic place-name that has been retained at other sites in the south – became an important trading place in the 6th century BC. The Volcae Tectosages fortified the oppidum.