An undiscovered section of Hadrian’s Wall has been uncovered in a busy Newcastle street while works on a water main were taking place.

The amazing discovery of the 1,900-year-old Roman fortification has been made after workers from Northumbrian Water were carrying out a routine mains replacement in the area.

A 3m section of the famous Wall about has been located below surface level and is believed to be from one of the earliest phases of construction of the historical landmark, as it was built using particularly large blocks of stone, whereas later phases used much smaller pieces.

According to English Heritage, Hadrian’s Wall stretches 117km (73 miles) from east coast to west. It was built on the orders of the emperor Hadrian, following his visit to Britain in AD 122, to guard the wild north-west frontier of the Roman Empire. The remains of the forts, towers, turrets and towns that once kept watch are still visible and Hadrian’s Wall is a UNESCO World Heritage Site.

Northumbrian Water were carrying out part of a £5m project in order to improve tap water quality to about half a million customers across Tyneside when the discovery was made.

Graeme Ridley, project manager from Northumbrian Water, said: “It is amazing that we have been able to make this brilliant discovery, and we are glad to be working with Archaeological Research Services to make sure that it is properly protected going forwards.

“This is an incredibly special part of North East heritage and we are honoured to be a part of it. We have completed work in the area and this vital work has been carried out in order to futureproof our water supplies and ensure that our customers continue to receive excellent and high-quality tap water.”

Philippa Hunter from Archaeological Research Services said: “Despite the route of Hadrian’s Wall being fairly well documented in this area of the city, it is always exciting when we encounter the wall’s remains and have the opportunity to learn more about this internationally significant site.

“This is particularly true in this instance where we believe that we uncovered part of the wall’s earliest phase. It is always a pleasure working closely with Northumbrian Water who take the preservation of archaeological remains such as these very seriously.”

Northumbrian Water, and their contractors Fastflow, confirmed that the pipe-route of the water main could be angled to leave a buffer around the excavated trench.

The water company’s pipe-cleaning programme taking place in the area will involve cleaning nine kilometres of strategic water mains at 18 different locations in and around Newcastle, Gateshead and North Tyneside. This is part of a larger £66 million cleaning programme, which began in 2010 and has seen improvements to more than 221 kilometres of strategic mains cleaned to date.

According to Ridley, the work is being carried out to futureproof water supplies and ensure that customers continue to receive high-quality tap water.