When you think of the National Trust, the first thing that springs to mind is often a quintessentially British scene of magnificent stately homes and well-manicured lawns. However, there is often much more to Trust properties than meets the eye...

From Roman defences, to anti-aircraft batteries - via castles, hillforts and pillboxes, today's 'sedate' National Trust has seen plenty of action throughout the course of history.

Here are just a taster of some of the sites that have helped to protect England, Wales and Northern Ireland:

Hod Hill, Dorset

© Martin Papworth

Hillforts are a characteristic monument of the Iron Age spanning the period from the eight century BC to the first century AD. Early archaeologists coined the term 'hillfort' but we think that these enigmatic structures may also have been used for gatherings, storage and redistribution, or ceremonial purposes.

The Iron Age fort at the top of Hod Hill is one of the largest in Dorset, its multiple ramparts once protected a large village. The Romans captured the fort around 44AD and built their own defences in the north-west corner.

Hadrian's Wall and Housesteads Fort, Northumberland

© NTPL / Paul Wakefield

Built between AD122 and 125, Hadrian's Wall is a spectacular reminder of the Roman occupation of Britain. Housestead's Fort is one of the best-preserved forts in the area, and must have appeared formidable to the potentially dangerous Northern tribes.

Clough Castle, Co Down

© NTPL / Joe Cornish

This Norman motte and bailey castle situated in Clough, was seemingly abandoned in the early 14th century. The 15th century saw the addition of a tower-house, which would have provided a superb view-point across the landscape for potential enemies.

Bodiam Castle, East Sussex

© NTPL / Alasdair Ogilvie

Often considered the last great English castle, Bodiam was built in the late 14th century by a local knight as a demonstration of his wealth and power. The defensive features that still survive today could well have had a more decorative than practical use, however, the castle represents what many still believe to be a traditional Middle Ages stronghold.

Chirk Castle, Wrexham

© NTPL / Matthew Antrobus

Sitting on the border of England and Wales, Chirk Castle was built in 1295 during the oppressive regime of Edward I. During it's 700-year history, the Castle was beseiged three times and served as a garrison for Royalist Troops during the Civil War.

The Needles Old Battery, Isle of Wight

© NTPL / Martin Trelawny

Constructed in the mid 19th century, initially to ward off the threat of invasion from the French, the cliff-top fort was used in both World Wars as a defence for the South Coast. Today visitors can explore the tunnels, ammo rooms and the two original gun barrels on display on the parade ground.

Orford Ness, Suffolk

© NTPL / Joe Cornish

Between 1913 and the mid 1980s, the shingle spit served as a secret test site for the military, although it had also been used as a line of defence from a potential Napoleonic invasion. Several buildings still stand as testament to the colourful history, including a Bomb Ballistics Building, the Martello tower and an armoured plate store.