The heatwave has uncovered a new historical site beside Newgrange in County Meath.

A circular enclosure, or 'henge', was captured in a field on drone footage at the Unesco World Heritage Site.

It is only visible at the moment due to the dry spell and it is believed to date from 2,500 BC, around 500 years after Newgrange was built.

The historian who owns the drone that captured the footage, Anthony Murphy, has been studying the archaeology of the Boyne Valley for many years.

Drone footage shows a possible henge, or circular enclosure, which may be of archaeological interest in the UNESCO World Heritage Site close to Newgrange in Co Meath. | https://t.co/1BMuh05WNX pic.twitter.com/fFFOJBs9X4 — RTÉ News (@rtenews) July 11, 2018

He told the Irish Independent that “the weather is absolutely critical to the discovery of this monument.

"I have flown a drown over the Boyne Valley regularly and have never seen this.”

He explained how the recent hot weather has revealed the new discovery, saying the moisture left in the soil “lodges in the archaeological features a little bit more than it does in the surrounding soil".

"The crop that is growing out of the soil is greener in the archaeological features and drier outside of them.

“So when that crop is harvested all surface traces of this monument will vanish and we may not see this monument again for 2 or 3 decades depending on when we get another prolonged dry spell like this.”

- Digital Desk