THE REMAINS of two castles, one up to 800 years old, have been found during a multi million overhaul of the water system in Glasgow.

Archaeologists have described the discovery of a 12th or 13th century castle in Partick, and one built on the same site 400 years later, as the "most historically significant in the city for a generation".

They found several stone walls, a well and ditches after being called in during work by Scottish Water on a new sewer overflow.

A spokesman for Scottish Water said they were expecting to find something, as the existence of Partick Castle has been documented, but were amazed to find two.

The excavations also uncovered fragments of pottery, metalwork, leather, glass and animal bones, estimated to date between the 12th and 17th centuries.

The spokesman said it was “remarkable” that the ruins survived the amount of industrial activity in the area over the centuries.

The discoveries were made in the Castlebank Street area on the north bank of the River Kelvin during preparations for a £3m Scottish Water project to install a new sewer overflow.

Hugh McBrien, of West of Scotland Archaeology Service (WOSAS), said: “No-one knew anything about the 12th century castle in Partick. There was documentary evidence that the bishops of Glasgow spent time in Partick and there have been historical references to ‘charters signed at Partick’. But that’s all.

“It has been known that there was a tower house or castle in the 17th century but all we had were antiquarian drawings and documents that refer to Partick Castle.

“So we expected there was archaeology in this area, because of historical records, but this discovery is the first hard, tangible evidence that both castles existed.

“This is the most significant archaeological discovery in Glasgow in a generation.”

Warren Bailie, project manager with Glasgow-based GUARD Archaeology, working on behalf of Scottish Water, added: “These findings made during Scottish Water’s work are of national significance and provide a rare glimpse into the medieval beginnings of Partick and Glasgow.

“The survival of these medieval remains is especially remarkable given that the site, not unlike many industrial river banks across Britain, has witnessed such large-scale destructive development over the centuries.”

Historical records show that Partick Castle was built near the confluence of the rivers Clyde and Kelvin as a retreat for the hierarchy of the Diocese of Glasgow, which was established in 1115 and occupied the castle until the Reformation in the 1560s. Simon Brassey, environmental advisor for Scottish Water, said: “The history of the area in this part of Partick is documented on old maps but it is only when the ground is opened up that you can fully understand what has survived 19th century industrialisation.

“As part of the project planning, Scottish Water identified the possibility of archaeology and so factored in time for the area to be pre-excavated. However, the discoveries are much more exciting than we had expected and we are delighted that, with the archaeologists’ help and expertise, we have been able to uncover something of such importance.

“Following these discoveries, Scottish Water will continue to do everything we can to assist the archaeologists in whatever way they require as their work progresses.”

The discoveries will be recorded, analysed and removed and, like all archaeological finds, claimed by the Crown.

Scottish Water’s upgrade to the Greater Glasgow area’s waste water infrastructure, the biggest since Victorian times, includes the £100m Shieldhall Tunnel and flooding projects such as a £12m investment in the Elmvale Row area of Springburn.