A section of Dublin's original 18th century sea wall has been discovered beneath a former electricity substation in the city's port.
The find was made during restoration and redevelopment work to the two-storey redbrick building located near the junction of East Wall Road and Alexandra Road.
Jim Kelleher, head of special projects with Dublin Port Company's heritage and communications team, said: "We have long suspected that part of the original sea wall may have lain beneath the old redbrick substation, which itself is a protected structure.
"But it has been incredibly exciting to have those suspicions confirmed, and to see this part of the original 'East Wall' for the first time."
It is thought the sea wall - a mixture of granite, sandstone and limestone kalp - dates back to the late 1720s.
It once enclosed the eastern and northern sides of newly reclaimed land that would become known as the North Lotts.
However, as the port extended eastwards away from the city, the sea wall's original purpose became obsolete.
"It runs all the way under East Wall Road and continues around to Ballybough Bridge," explained Niall Brady, director of ADCO, the Archaeological Diving Company Ltd.
"It is an engineering marvel which helped to define the northern extension of Dublin city at a time of monumental change. And it is largely unknown to Dublin residents today because we have built over it as the port has been extended."
The discovery of the wall was made during works being carried out by building contractors Dunwoody & Dobson on the former substation.
Project manager Mark Hughes said: "It has been quite a complicated, slow process. We have had to try to ensure the substation stays standing while we try to salvage it, clean it and maintain it. At the same time, we are building a new building next to it. The finding of the wall though was a delight. It's brilliant."
A number of dockworker artefacts were also found during the works.
These include several clay pipes embossed with trade union and political logos, including a Parnell MP pipe thought to be one of the earliest examples of political campaign support merchandise in Ireland.
Leather shoe parts belonging to dockworkers, as well as 19th century pottery fragments, glass and bone have also been recovered for preservation.
Dublin Port Company’s plans for the substation building include installing a glass panel feature floor, enabling visitors to view the exposed sea wall.
The permanent display will be part of a 6.2km cycle and pedestrian route linking port, maritime and industrial heritage landmarks.
Lar Joye, Port Heritage Director said: "Between the wall itself and the artefacts uncovered, this represents a significant find by any standard.
"It not only furthers our understanding of the city's development eastwards, but also the lives and political leanings of dockworkers of the day.
"We look forward to sharing our discovery and telling these stories when the redbrick Victorian substation opens to the public in early 2023."