Workers installing a new sewer line in Scotland unexpectedly uncovered ancient human remains, as well as evidence of a much older settlement.

The burial site dates back to the 6th century AD, according to a Jan. 28 press release from Scottish Water.

It was found at Windhill in the Scottish Highlands.

Remarkably, archaeologists also found two roundhouses from the Iron Age — which may date back as far as 3,000 years.

Excavators also found stone tools and two smelting furnaces, which “would have been housed in structures outside the roundhouses,” Scottish Water said.

“The furnaces would likely have produced significant heat and fumes, precluding them from being set within an enclosed space,” the release added.

“This is evidenced by the arcs of post holes that were much shallower than the settings for the roundhouses and likely formed ancillary, temporary structures.”

Artifacts and environmental materials from the site can reveal “much about daily life,” both during the Iron Age and the 6th century AD, said Steven Birch, an archaeologist at West Coast Archaeological Services.

“The two smelting furnaces and a smaller [blacksmith’s] hearth were relatively well-preserved and during the excavations I was able to reveal much detail about their construction and use,” he said.

One of the 6th-century burials had been placed in a log coffin, Birch said — and although most of the remains did not survive, a soil stain marked where it had been laid, along with a few cranial fragments.

“There were no grave goods, which is typical of graves from this period in Scotland — unlike the well-furnished Anglo-Saxon burials of this period in England.”

Experts were aware that the site held some archaeological potential, as “a large number of prehistoric features” were found a few years ago, Birch said.

Birch also described the condition of the two prehistoric roundhouses as “excellent,” contributing to new evidence of a settlement at the site.

“Within a wider context, these types of discoveries add to a growing corpus of sites around the Moray Firth Basin, suggesting the area was a well-populated one during prehistory, and with widespread evidence for industrial activities including metalworking,” he said.

He added, “These sites produced no pottery, but [rather] a range of stone tools for grinding grain, some small fragments of copper-alloy, and iron objects, which require further analysis.”

He also said, “Environmental materials recovered from bulk samples include charcoal, burnt hazelnut shell and some burnt grain… likely six-rowed barley.”

Because the soil is highly acidic, few bones survived from the burial site, though several fragments were recovered.

The most surprising discovery was clay daub in the roundhouse — or mud plaster that was used to cover woven wooden walls.

What made the daub so unusual was its decoration — particularly its chevron, or V-shaped, patterns.

“I can confirm that such decoration is incredibly rare and this is the first instance found within Scotland, if not the U.K., although additional research is required here,” he said.

He also said that, by the time that 6th-century people lived there, some evidence of the earlier Iron Age roundhouses was still visible.

“We know that, during the early medieval period, although Christianity was coming to the fore, people still had respect for [their pagan] ancestors, and that prehistoric standing stones and earlier burial monuments were linked to the deep past and ancestors,” he said.

“These later barrows are often focused on these earlier monuments.”