Swords Castle will be lit up green for St Patrick's Day and its grounds will also be open to the public from then onwards.
Fingal County Council confirmed the "greening" of the castle to the Herald.
The grounds have been closed to the public for regeneration works for more than a year, but locals will soon be able to walk within its walls again.
The news follows the announcement that €3m has been ear-marked for works in the castle area between 2015 and 2017.
In 2015, €1.5m will be spent to regenerate the castle and its environs. The development of the area is part of a newly-announced architectural master-plan for a civic and cultural focal point for Swords.
Fianna Fail councillor Adrian Henchy welcomed the reopening of the grounds saying the castle is the traditional "heartbeat" of the town.
"It does look like there's now a definite movement on the castle and it's going to be a major project.
"It's almost been stuck in a time-warp for years but when I was growing up it was the heartbeat of the area," Cllr Henchy said.