COLCHESTER, perhaps, has no greater defining characteristic than its Roman town wall.

As one of only 300 scheduled monuments in the country, it is a great source of civic pride.

And so it is the vandalism, not by warriors but yobs with spray paint, is so bad.

The wall is the earliest stone built defence structure of its kind in the country, dated to AD 65-80, and was built following the Boudican Revolt in AD 60, which saw the violent destruction of the town.

The wall formed a circuit 2,800m long and 2.4m thick. The original height is not known and the highest surviving part is 2.6m above modern ground level but it is thought the original height may have been over six metres.

It has stood for nearly two millennia, directing the geographic and historical development of the town and nearly two thirds of the circuit is visible today, with the remainder surviving as buried archaeology.

Six gates were built into the Roman Wall. The town’s main entrance from the west, the Balkerne Gate, which incorporated a free-standing monumental arch built to celebrate the Claudian conquest of Britain, probably in the AD 50s and faced with stone brought especially from the Hampshire coast.

This monumental arch was incorporated into the town wall, creating a double-arched gateway with flanking walkway arches and external guardrooms. It was 30m wide in total.

The archways formed the main carriageways with the addition of a footway and a bastion on both sides. The surviving pedestrian archway, is still in use today and southern bastion is only a small part of what was once a major entrance into Colchester.

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Photos: Rodger Tamblyn

A distinctive mud stone, septaria, was imported from near Harwich and used as the main building material. In the absence of good local building stone, this was supplemented by courses of tile.

The faces were raised, a few courses at a time, and the space between the two faces was filled with layers of septaria and lime mortar.

The wall was not raised as one unit all round its circuit. Instead, it was built in short 40m to 60m sections by a number of ‘gangs’, each almost certainly working at their own speed and, to a limited degree, building them in their own way.

Detailed analysis by the Colchester Archaeological Trust of the Balkerne Gate and the wall to either side of it has identified five different sections of wall, constructed by five different gangs – one for the gate and four for the stretches of wall.

The gang which built the gate favoured pink mortar containing crushed and powdered brick while the gang which built the section to the north of the Balkerne Gate favoured the use of waste from dressing the facing stones as aggregate in their mortar mix.

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Historic - Colchester’s famous Roman wall

The distinctive Roman character of the wall is still very evident, although the continued defensive importance of it during the Medieval and Civil War periods is clear.

Eight bastions were added along the south-east circuit in the 14th century, several of which can be seen from Priory Street car park. The defences suffered significant damage during the Civil War Siege of 1648, beginning a period of post-medieval robbing and collapse.

Colchester Council cares for the wall under a Heritage Partnership Agreement with Historic England. Under the council’s property management arm, Colchester Borough Homes, there has been a major programme of repairs and maintenance over the last few years to ensure the wall is preserved for future generations.

The conservation work is being carried out by Stone Technical Services, experts in historic building restoration and maintenance.

The materials used must match the existing appearance of the wall as closely as possible in order to preserve its character.

Generally, this involves repairing masonry which has become loose, using a traditional lime, sand and aggregate mortar mix, in keeping with existing mortars used on the wall. Modern concrete which was used - critics say inappropriately - for repairs in the past has been replaced with lime mortar, wherever it is loose.

As well as its historical importance, the wall is also a designated local wildlife site which provides a rich habitat for a wide variety of rare plant and insect life which has colonised it over the millennia.Gazette:

Volunteers from the Colchester Natural History Society have been recording the flora on several sections of the wall to ensure the repairs do no ecological harm.

Some plants – self-setting bramble, elder, ivy, and similar flora – could damage the fabric of the wall, and these need to be carefully removed by hand-weeding and spot treatment of woody stumps.

The majority of plants, however, do no damage to the fabric and the council is working with experts to ensure repairs minimise the disturbance to wildlife.

Tim Young, Colchester councillor responsible for culture, said: “Colchester’s Roman Wall provides visitors with perhaps the most stunning visual reminder of the long and momentous past that is woven into the fabric of our town, and which most vividly defines its unique status as the oldest recorded settlement in Britain.

“As custodians of such a unique and irreplaceable monument, I am pleased the council is set to launch a new management plan for the Roman Wall later this year, which will provide a framework for its maintenance, enhancement, interpretation, presentation, nature conservation and setting over the next five years.”