Scientists were today investigating the "significant and unexpected" discovery of what is believed to be an early 19th century time capsule.
The find was made in Dublin’s O’Connell Street where an excavation firm was digging at the former site of a monument to Lord Nelson in preparation for the erection of the Millennium Spire.
Accompanied by archaeologists they unearthed a box which is now undergoing tests before it is opened.
"The team came across this stone, round box and inside that, as I understand it, there is a metal capsule and inside that a metal capsule," said National Museum director Pat Wallace.
"I hope our expectations haven’t been built up too much because it hasn’t been opened yet," he said.
It is believed that the capsule dates back to 1808 when the monument to Lord Nelson was built, shortly after his death.
Experts will now subject the artefact to tests and X-rays before prising open the metal casing at the National Museum’s £6m laboratory.
"It will be opened very carefully in a museum laboratory. The metal will have to be prised open and we will have to look at the contents very carefully," Dr Wallace said.
"If anything in it is organic like paper or leather we will have to make sure that everything is retrieved without any contamination."
He added: "If it isn’t a capsule, God knows what it is."