A ringwork is a form of fortified defensive

Defense (military)

Defense has several uses in the sphere of military application.Personal defense implies measures taken by individual soldiers in protecting themselves whether by use of protective materials such as armor, or field construction of trenches or a bunker, or by using weapons that prevent the enemy...

 structure, usually circular

Circular

Circular is a basic geometric shape such as a Circle.Circular may also refer to:-Documents:*Circular note, a document request by a bank to its foreign correspondents to pay a specified sum of money to a named person...

 or oval

Oval

An oval is any curve resembling an egg or an ellipse, such as a Cassini oval. The term does not have a precise mathematical definition except in one area oval , but it may also refer to:* A sporting arena of oval shape** a cricket field...

 in shape. Ringworks are essentially motte-and-bailey

Motte-and-bailey

A motte-and-bailey is a form of castle, with a wooden or stone keep situated on a raised earthwork called a motte, accompanied by an enclosed courtyard, or bailey, surrounded by a protective ditch and palisade...

 castles minus the motte

Motte

Motte may be:*Motte-and-bailey, a type of construction used in castles*Isaac Motte, an 18th century American statesman*La Motte , various places with this name-See also:* Mote * Mott...

. Defences were usually earthworks

Earthworks (archaeology)

In archaeology, earthwork is a general term to describe artificial changes in land level. Earthworks are often known colloquially as 'lumps and bumps'. Earthworks can themselves be archaeological features or they can show features beneath the surface...

 in the form of a ditch

Ditch

A ditch is usually defined as a small to moderate depression created to channel water.In Anglo-Saxon, the word dïc already existed and was pronounced 'deek' in northern England and 'deetch' in the south. The origins of the word lie in digging a trench and forming the upcast soil into a bank...

 and bank surrounding the site.

Ringworks originated in Germany in the 10th century as an early form of medieval castle and at first were little more than a fortified manor house

Manor house

A manor house is a country house that historically formed the administrative centre of a manor, the lowest unit of territorial organisation in the feudal system in Europe. The term is applied to country houses that belonged to the gentry and other grand stately homes...

. They appeared in England just prior to the Norman conquest and large numbers were built during the late 11th and early 12th centuries. More elaborate versions comprise a ringwork and bailey, the ringwork replacing the more usual motte and the bailey acting as a military stronghold.