Get the biggest stories sent straight to your inbox Sign up for regular updates and breaking news from WalesOnline Thank you for subscribing We have more newsletters Show me See our privacy notice Invalid Email

This tomb is 5,000 years old and on the longest day of the year a beam of sunshine shoots down its main passage, lighting up the entire chamber.

And archaeologists have now discovered that the tomb, which was used for thousands of years, was actually much bigger than previously thought.

Experts used 3D digital modeling at the Neolithic passage tomb, Bryn Celli Ddu, or the “Mound in the Dark Grove”.

It is one of Wales’ most impressive and evocative ancient historical sites, and over the last three years a public archaeology project has grown around it.

(Image: Cadw)

Thought originally to be a single passage tomb it now appears that the was an entire complex of cairns around the site that developed over time.

A cairn is a man-made pile of stones which is often used to mark a burial site. When made of earth, it is called a barrow.

And it now appears that at Bryn Celli Ddu there was a cairn complex or cairn cemetery.

(Image: Cadw)

The site has been studied by experts from Manchester Metropolitan University, the University of Central Lancashire and Cadw.

Dr Ben Edwards, from Manchester Metropolitan, said: “We hit the fields with different geophysical techniques and we found at least four burial cairns.

“We originally thought it was lone monument but now we know there are four. It seems a complex developed over many years. We call it a cairn cemetery. It is from the neolithic through to early bronze age.”

It appears that site has seen human activity for several millennia and with several examples of rock art identified as well.

Dr Seren Griffiths, from the University of Central Lancashire, said: “We know that Bryn Celli Ddu sits in a much more complicated landscape than previously thought. Over the last three years, we have discovered 10 new rock art panels and this year the picture has developed to include further evidence for a new Bronze Age cairn along with a cluster of prehistoric pits.

“We have evidence for over 5,000 years worth of human activity in the landscape, ranging from worked flint derived from the tool-making efforts of our prehistoric ancestors to prehistoric burial cairns and pits with pottery deposited within.”

(Image: Manchester Metropolitan University)

This rock art is described as having an “incredible” blue colour. Dr Edwards said: “We don’t dig the monument itself but have investigated the landscape. We have looked at the rock art. This is an incredible blue colour but also has colours like gold and fool’s gold.

“We found that about 10 more rock outcrops with this carved art. Unless you know what you are looking for they are hard to spot.”

Another fascinating element to the site is the style of many of the monuments.

“Interestingly this is not a typically British monument,” said Dr Edwards.

“It is much more like what you find in Ireland and this was not coincidence. They were communicating around the Irish Sea.”

(Image: Aerial-Cam Ltd)

According to Dr Edwards it is unsurprising that the ancient people who lived in the area turned to the sea as way of communicating. With little in the way of roads, the ocean was the speedier option for travel.

He said: “Remember back then you were travelling mainly through partially cleared forest so the sea was the easiest mode of transportation.”

Over the last three years, much of the work of excavating and exploring the area around the site has been done by community volunteers.

Dr Ffion Reynolds, from Cadw, said: “Since we started the project we have discovered that Bryn Celli Ddu was never in isolation, there was activity happening all around.

“We knew this would be a good project but it’s turning out to be very exciting.”