The moat surrounding the Rampton castle site is now a pretty haven for wildlife
Walk back in time to the mid-1100s when Cambridgeshire was at the heart of a civil war.
Matilda had inherited the throne from her father, Henry I, but her cousin Stephen snatched it from her.
The ensuing breakdown in law and order led to King Stephen ordering his people to build anarchy castles in the worst hotspots.
One was at Rampton, near Cambridge, and people discovered its history during a guided walk on 14 July 2010.
This time in English history is known as The Anarchy. The monks at Peterborough Abbey wrote an account of the times in the Peterborough Chronicle. The lawlessness resulted in people unable to plant crops so they starved and, the monks claimed, "said openly, that Christ slept, and his saints".
A baron called Geoffrey de Mandeville was one of those who exploited the weakness of the throne. The Essex man took over the Isle of Ely. He used it as his base and forayed forth, sacking Ramsey Abbey, burning Cambridge and generally ravaging, robbing and pillaging.
King Stephen was determined to curb his excesses, so he ordered lords loyal to him to ring the Fens with castles. These are now known as anarchy castles.
In Cambridgeshire they were also built at Burwell, and possibly at Woodwalton and Swavesey.
View across the pasture from the medieval village site to the church
However, they were certainly not intended to protect the people from Geoffrey de Mandeville's rampages but instead to reassert the king's power.
"It's the feudal period, a time when if you were anybody who wasn't either in the clergy or the nobility, you were at the bottom of the pecking order," explained Stephen Macauley, from Oxford Archaeology East.
"And here at Rampton, the people who had to build the castle were the local peasants. Not only were they told they had to lose their houses, then to add insult to injury, they had to come up and start building the castle themselves."
So the site includes the remains of a medieval village as well as the castle's earthworks.
In the end the villagers suffered in vain. The castle was never completed.
They got as far as knocking down their houses, digging out a moat and piling up a castle mound when Geoffrey de Mandeville died from wounds acquired while besieging Burwell castle.
King Stephen decided there was now no need for Rampton to be finished and, having gone to the trouble of clearing the site, the local lord decided not to allow the villagers to rebuild their homes.
Visitors cross the moat via a boardwalk to reach the castle site
"Rampton is a very small village and we're surrounded to our north and west by the large village of Willingham, and over to our east is the large village of Cottenham," Stephen Macauley explained.
"I suspect that if you go back to the medieval rolls you'd probably find the names of people here ending up in these villages of Cottenham and Willingham."
Over the next 800 years the site was mostly used for grazing. The remains of the village lay undisturbed and a manor house appears to have been built in the later Middle Ages but today the site is peaceful pasture.
Soldiers returned to the castle during World War II. A gun was placed in the centre of the castle mound, manned by the Home Guard, and visitors can still see its concrete base.
This particular medieval civil war was only resolved by the Treaty of Wallingford, which made Matilda's son Henry Stephen's heir. He came to the throne as Henry II in 1154.
The Rampton site is a Cambridgeshire County Council pocket park and a haven for wildlife. The moat is now filled with water because water levels have changed, but as recently as 60 years ago it was dry.
The public was invited to discover the story of Rampton's anarchy castle during a guided walk led by Sally Thompson, from Oxford Archaeology East.
The company's archaeologists provide free guided walks for Cambridgeshire County Council and it does not receive any subsidy from the taxpayer.