While installing a drain filtration system on the grounds of Castle Ward in County Down, the foundations of a courtyard and surrounding buildings were discovered in a densely vegetated region.

Archaeologists have been caught completely off guard by the finding at the National Trust site because no historical maps or papers of the estate mention the structures.

It was discovered during the excavation of a trench to transport a pipe from Castle Ward's existing structures to a reed bed.

At the time, archaeologists were on the job site keeping an eye on the excavation in case anything important was discovered. But as the first few red bricks were exposed, they were taken aback by what they saw.

For the first time in three centuries, the remains of a group of buildings were revealed as the topsoil was further removed.

A number of structures, some with flagged and tiled floors, surrounded a central cobbled courtyard.

There is a network of stone-lined drains, a cellar, a fireplace and a washbasin. Numerous items have also been discovered, including as glass bottles, ceramics, earthenware, and abandoned, slaughtered animal bones.

The current country residence at Castle Ward was first constructed in the 1760s, but an earlier home from the early 18th century existed before it.

The recently found ruins, according to experts, may have been a household and agricultural complex of structures used by the first Castle Ward house and date to the late 1600s or early 1700s.