Z Plan is a form of castle design common in England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 and Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

. 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

Glenbuchat Castle

Glenbuchat Castle is an historic Z plan Scottish castle built in 1590 for John Gordon of Cairnbarrow to mark his wedding. It is located above the River Don, near Kildrummy, Aberdeenshire. The building is roofless, but otherwise in fairly good repair....

 in Aberdeenshire

Aberdeenshire

Aberdeenshire is one of the 32 unitary council areas in Scotland and a lieutenancy area.The present day Aberdeenshire council area does not include the City of Aberdeen, now a separate council area, from which its name derives. Together, the modern council area and the city formed historic...

, Castle Fraser

Castle Fraser

Castle Fraser is the most elaborate Z-plan castle in Scotland and one of the grandest 'Castles of Mar'. It is located near Kemnay in the Aberdeenshire region of Scotland. The castle stands in over of landscaped grounds, woodland and farmland which includes a walled kitchen garden of the 19th...

 in Aberdeenshire and Hatton Castle

Hatton Castle

Hatton Castle stands on the lower part of Hatton Hill, the most easterly of the Sidlaw Hills, to the south of Newtyle in Angus, Scotland. The castle overlooks the wooded Den of Newtyle, and its views extend across Strathmore and include Ben Lawers and Schiehallion as well as the Angus and Glenshee...

, Angus

Angus

Angus is one of the 32 local government council areas of Scotland, a registration county and a lieutenancy area. The council area borders Aberdeenshire, Perth and Kinross and Dundee City...

, Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

.

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.