Segedunum was a Roman fort at modern-day Wallsend, North Tyneside in North East England. The fort lay at the eastern end of Hadrian's Wall (in Wallsend) near the banks of the River Tyne, forming the easternmost portion of the wall. It was in use as a garrison for approximately 300 years, from around 122 AD, almost up to 400AD. Today, Segedunum is the most thoroughly excavated fort along Hadrian's Wall, and is operated as Segedunum Roman Fort, Baths and Museum. It forms part of the Hadrian's Wall UNESCO World Heritage Site. Etymology Five places named Segedunum are known to have existed in the Roman empire, one each in Britain and Germany and three in Gaul. The name Segedunum is known from the Notitia Dignitatum of the 4th century, but there is no consensus on its meaning. The various conjectures include "derived from the Celtic for 'powerful' or 'victorious'", "derived from the [Celtic] words sego ('strength') and dunum ('fortified place')", "Romano-British Segedunum 'Strong-fort'", and "Celtic sechdun or 'dry hill'". The first element of the name is attested widely in Gaul, Spain, Germany and Italy, and derives from the Indo-European root segh-, which is reflected in various later European languages with similar meanings: Irish seg-, segh- 'strength, vigour', Welsh hy 'daring, bold', German Sieg 'victory', and so on. As applied to place names, it appears to have had the meaning of "place of strength" or "place of victory". The second element, -dunum, is a Celtic term widely attested across Britain and Gaul and typically meant a fort. Thus Segedunum probably had the meaning of "strong fort" or "victory fort". History The Roman wall originally terminated at the fort of Pons Aelius (Newcastle upon Tyne). Work began at Pons Aelius in 122AD and proceeded towards the west. Subsequently, in about 127AD, the wall was extended further east, possibly to protect the river crossing at Pons Aelius. A section of the wall east from the fort of Pons Aelius, passing through present-day Byker and ending at the new fort of Segedunum was built. The new section of wall was narrower than the sections previously built, being on a foundation of . Unlike the rest of the wall, the extension had no Vallum running south of it. This was a large ditch with parallel earth banks on either side of it, an extra line of defence that was added behind the rest of the wall