County Meath: See
Brú Na Bóinne Archaeological Park is a must-see, but Newgrange tomb interior can fit very few visitors.
Hill of Tara was where the high kings of Meath were inaugurated.
Castles: the best by far is at Trim.
Religious ruins at Trim, Bective and Slane.
Ancient mounds 2500 years old at Telltown, and megalithic tombs at Loughcrew near Oldcastle.
High Crosses in Kells, but the famous book is now in Dublin.
The Battle of the Boyne, fought on 1 July 1690, spelled the end of James II's campaign to keep his throne. Henceforth Britain and Ireland were ruled by the Protestant Hanoverian dynasty of King William III. The visitor centre is on the road to Slane, though it's more easily reached from Drogheda.