Castle

Castles are borne in heraldry of different structures, and unless particularly described, are generally depicted with towers, port and loopholes as above. They are also often depicted as but one of the towers. This bearing is sometimes termed a port between two towers and a wall with battlements and gate between two towers, though castle seems the most proper blazon. The buildings are almost invariably borne masoned and, when the cement is of a particular tincture, it would be termed masoned of that tincture. When the windows and ports of castles differ in colour from the building and field, they are then considered to be shut, and must be so expressed in the blazon: but if the windows and ports are of the tincture of the field, which is seen through them, they are then open, or what is termed voided of the field, and should be thus described. When the port is defended by a portcullis, it should likewise be particularly noticed in the blazon.
A castle blazoned with four towers is represented in perspective as a quadrangle with a tower at each corner as on the left.. Castles with four towers are sometimes blazoned two towers in pale and two in fess as illustrated below. These are also represented in perspective, but one angle is placed closer to the spectator, whereas in the former, one side of the square is in the foreground.
 

Castle with four towers or a square tower.

 A castle blazoned with four towers is represented in perspective as a quadrangle with a tower at each corner as above. Castles with four towers are sometimes blazoned two towers in pale and two in fess as illustrated below. These are also represented in perspective, but one angle is placed closer to the spectator, whereas in the former, one side of the square is in the foreground.

Castle with the four towers domed and placed two in pale and two in fess  [Rawson] or a square castle towered. 

A tower is often blazoned as a castle

Castle breached on a mount, the French co1ours struck [Stibbert]

Triangular tower. The fore half of a castle with only three towers shown. These are represented in perspective, with one angle placed closer to the viewer.