Z Plan is a form of castle design common in England and Scotland. The Z-plan castle has a strong central rectangular tower with smaller towers attached at diagonally opposite corners. Examples of the Z plan are Glenbuchat Castle in Aberdeenshire, Castle Fraser in Aberdeenshire and Hatton Castle, Angus, Scotland. A variant on the Z plan is the C plan, in which the two smaller towers are attached at adjacent corners of the main tower.