Londinium - Lundenwic/Lundenburh - Londres - London. The transition from Roman Provincial capital to Anglo-Saxon trading town/fort to Norman French capital to world city is a long and colourful one. The 'bones' of the Roman settlement are still there, but you have to dig hard (or look where someone else has already dug) to find them.
English Heritage is an official body which is tasked with looking after historic buildings and other structures - its other title is the Historic Buildings and Monuments Commission for England - and it has many Roman sites under its protection. For example, it manages the Birdoswald Fort and Chester's Bridge Abutment on Hadrian's Wall and the Reculver Roman Fort on what was known as 'the Saxon Shore'.
Here we can see one of English Heritage's best known pieces of London's Roman heritage! Called simply London Wall, it lies immediately north of the Tower of London, near the Tower Hill Underground Station; as a matter of fact, the easiest way to reach this section of wall is to take the 'tube' to Tower Hill, and the Wall, a statue to the Emperor Trajan and a reproduction of the tombstone of Gaius Julius Alpinus Classicianus, the Procurator (finance minister) of the Province of Britannia from AD 61 to his death in AD 65, is right next to the exit from the station.
It is hardly surprising the wall is so close to the Tower as its Norman builders incorporated parts of the existing Roman wall into their 'new' structure. The wall was constructed in around AD 200, from Kentish ragstone rubble, bound with hard mortar and bonded with layers of red Roman tiles every five or six courses, to increase the strength of the wall, and to keep the wall level as it was built. This 'red banded' appearance is typical of Roman structures. The wall was finished off using roughly squared blocks of more Kentish ragstone; it is estimated that it would have taken 85,000 tonnes of stone to build the wall, and the project would have caused a boost to the local economy - rather like a WPA project! Who built it? It is highly likely that the engineers attached to every Roman Legion - they built everything from forts to bridges to roads - would have handled the job. The original structure was around 20 feet high, and was designed to surround the city of Londinium, an area of approximately 330 acres - a distance of close to 3 miles. In front of the wall was a fossa or ditch, 6 feet deep and 20 feet wide to increase the effectiveness of the fortification.
It is thought that the Pictish invasion of the north of the province of Britannia, in around AD 200/220, would have stimulated the thickening of Londinium's defences. It was, after all, the largest building project, after Hadrian's Wall, in the whole of the Province.
The Roman Legions were finally withdrawn in AD 410, and the city virtually abandoned. It wasn't until Mediaeval times that the wall was strengthened and increased in height. If you look closely at the photograph, you can see the top portion is different to the original work, lower down. For hundreds of years the wall defined the limits of the city, and buildings became more and more tightly-packed. The structure began to be 'mined' for its stone for other buildings, and, eventually, the city burst at the seams. Building took place around and on both sides of the old wall, and it was quickly obscured and gradually demolished, the greatest destruction coming in the 18th and 19th centuries (for example, a fine Roman tower near this section of wall was not destroyed until 1852!)
Fortunately, a few good examples of this most impressive Roman structure - including some later Roman bastions from the 3rd and 4th centuries AD - have been saved, thanks to English Heritage. Enough to remind all visitors that this was once a proud Roman city.