Bones were discovered during Luas work outside Trinity College on Dublin’s College Green this afternoon.
Gráinne Mackin, Director of Communications for Luas Cross City, said the bones were discovered about 1.5 metres deep.
She said that on first visual inspection they appear like historic human remains, which may be medieval.
Archaeologists were called to the scene and it was cordoned off.
The work could take a number of days, however Ms Mackin said Luas works are continuing outside the cordoned off area.
Ms Mackin said that the Department of Arts, Heritage and the Gaeltacht and all relevant authorities had been informed.