The N3 used to start on the N2 in Dublin and proceed around Phoenix Park, the residence of the Irish President. The road bypassed Castleknock and approached the M50 as a dual carriageway. Since the recent de-trunking programme, the N3 now starts here, and the old road is the R147. This major junction, like many others on the motorway, consists of a roundabout, much to the distaste of the locals. The road, still the normal N3 dual carriageway, bypasses Blanchardstown, Mulhuddart and Clonee before becoming the M3. The M3 was opened on the 4th of June 2010 and has two tolls between Clonee and Kells, whose fares have been increased recently. One toll is north of Navan, the other between Dunshaughlin and Clonee and now charge €1.40 each.
It snakes through the Meath countryside, past the Hill of Tara (The hill that gave the planners a headache) and comes to a grinding halt on a roundabout with the N52 Kells Bypass. Afterwards the dual carriageway continues as the all-purpose N3 for a few more kilometres before stopping on another roundabout with the R147. Now on the old course, it follows a predominately straight north-west course to Virginia. At this stage there are some bends, but none are N16 standard. The road continues north-west, passing through Cavan countryside until we hit the next "urban" conurbation at Lavey. The road now travels through Ireland proper- more hills than there are people. Eventually the road turns right at a roundabout with the R212 (straight on) and the N55 . After negotiating the Cavan Bypass we head through Butlersbridge and Belturbet, the road getting progressively narrower as we reach the border at Aughalane.
Across the Donegal border, the N3 was formerly a Regional road, before the NRA extended the low quality N3 by seven kilometres. The road itself is unremarkable, running through trees to the south of the River Erne as it heads for the coast. It terminates on the N15 , the new Ballyshannon bypass.
The N3 is primarily single carriageway. The dual carriageway (which includes 51km of new motorway and is designated M3) starts in northern Meath and was opened in 2010. The old, single carriageway N3 is now the R147.
The bridge crossing the Cavan/Fermanagh border at Aghalane was destroyed during the troubles. It remained closed until plans in the 1990s as part of the peace process sought to restore the crossing. The N3/A509 was realigned from a new roundabout at Staghall (N87) outside Belturbet across a new bridge named Senator Mitchell Peace Bridge west of the original crossing into Northern Ireland. This opened in 1999.
Later that year, 9.5 km of single carriageway bypassing Cavan and Butlersbridge opened. This was eventually linked to Staghall Roundabout by 6.7 km of single carriageway bypassing Belturbet in 2014.
Construction of the dual carriageway was somewhat controversial because it passed very close to the Hill of Tara, a heritage site. Plans did go forward to move it, but failed and the dual carriageway still passes close to the famous hill where the High King lived.