It's an ancient longhouse that is reckoned to have been built in around 800 AD, which is decades earlier than the Vikings were thought to have colonised that part of the world.
Oh, and it was found beneath another slightly less old longhouse that was packed with treasure, according to archaeologist Bjarni Einarsson, who was in charge of the excavations at the site.
He told Live Science that the longhouse above was probably that of a chieftain, saying: "The younger hall is the richest in Iceland so far.
"It is hard not to conclude that it is a chieftain's house."
So, in case you're wondering, a longhouse would have been a large hall made out of wood that could stretch to about 75 metres long, and been six metres wide.
Long and thin, hence the name.
They were commonplace across what is now Scandinavia and beyond during the era in which the Vikings were prominent.
A lot of the time they would be divided up into several homes for a number of families, but also provided stabling for the animals and had large stone fire hearths in the centre that could have been for communal gathering.
These particular longhouses have been unearthed in the east of Iceland at a place called Stöð - easy for you to say - and the youngest one is thought to have been built in around 874AD.
Now, that's about when people reckon that the Vikings arrived in Iceland, as the story goes, to escape the clutches of Harald Fairhair, the Norwegian king.
This longhouse found beneath it calls that date into question, and suggests that Iceland could have been inhabited by people several decades earlier than that.
In fact, this older structure could be evidence of a temporary camp settlement occupied by workers in the region for the summer months.
As for the younger, more permanent house, it contained a hoard of treasure that included loads of ornamental beads, as well as coins made out of silver and gold.
Einarsson claims that it is one of the most valuable hoards ever discovered in Scandinavia.
As well as Viking stuff, there are also Roman and Middle Eastern coins, and 'hacksilver', a type of currency made out of cut or bent pieces of silver.
Parts of the older longhouse show that it's one of the largest longhouses ever discovered in Iceland, and featured a smithy in the hall.
That's interesting, because it's the only one known to modern archaeology in Iceland.
Einarsson added: "We know that the westernmost part of the older hall was a smithy [for working with metal] - the only smithy within a hall known in Iceland."
This temporary camp follows the pattern shown at places like Newfoundland in Canada, whereby the Vikings branched out their civilisation by colonising in a temporary fashion, before creating permanent settlements later.
"This was a pattern of the settlement of the islands in the Atlantic Ocean," Einarsson said. "First, we had the seasonal camps, and then the settlement followed."
The project, run by Einarsson's private archaeological firm, has been paid for by Iceland's archaeological fund, as well as the local government, companies and people.
Chosen for YouChosen for You
Most Read StoriesMost Read