Dublin city councillors have voted against a land swap deal that would have ensured the restoration of the 1916 Easter Rising site in Moore Street in time for centenary celebrations.
Officials had proposed accepting an offer from developers Chartered Land to restore the national monument at 14-17 Moore Street as a heritage centre and give it to the council.
The developers made an improved offer to include No 10.
The buildings were used by 1916 rebels as they tried to break out through British lines and for their last council of war.
In exchange for the €9 million NAMA-funded project, the council would give the developers the site it owns at 24/25 Moore Street, which is needed for a shopping centre.
However, some relatives groups want to preserve the entire terrace and surrounding area as a battlefield site.
Under the plans for the shopping centre the remaining buildings on Moore Street would be demolished.
However, Chartered Land has said that many of the buildings have been rebuilt since the Rising.
Sinn Féin, Fianna Fáil, People Before Profit and Green Party councillors voted against the deal.
Some independents, Labour and Fine Gael councillors were in favour.
The final vote was 38 against with 22 in favour, with a number of abstentions.