1221 - Designed and constructed by the Norman Theobald FitzWalter, the first Butler of Ormond who dies before it's completion.
1336 - peace treaty signed in Castle between the O'Kennedy Clan and James Butler, 1st Earl of Ormond, treaty includes grants of lands for this Gaelic clan.
1347 - taken from the Butler's by Donal O' Kennedy. Held by the O'Kennedy Clan for two centuries.
1385 - James Butler, 3rd Earl of Ormond builds Gowran Castle, Kilkenny and establishes it as their principal seat, then in 1391 buy's Kilkenny castle and establishes it as their principal seat.
1533 - repossession of castle by Piers Butler, 8th Earl of Ormond.
1548 - attacked by O'Carrol's, town and Franciscian friary burned.
1648 - captured by Owen Roe O'Neill and his Ulster Army during the Confederate War as they marched on Kilkenny following the Royalist and Confederate truce during the Confederate War. Castle is quickly wrested back by Lord Inchiquin for the Earl of Ormond.
1650 - The Parlimentarian Ireton captures the castle on his march on Limerick.
1688 - captured, lost and recaptured by the Jacobite Colonel Long Anthony O’Carroll who is serving under Sarsfield.
1690 - captured by the Williamite Dutch general Godert de Ginkell.
1692 - listed by King William of Orange for destruction, this is in order to permanently render it useless to opposing forces.
1750 - farmer named Newsome attempts to demolish the castle with explosives as sparrows nesting in the walls are destroying his crop. His attempts however only succeed in creating a large whole in the in the north wall of the keep.
1860 - The upper quarter of the castle added by Rev Michael Flannery the Bishop of Killaloe with the proposal that it would form part of a proposed new Roman Catholic Church for Nenagh. This idea is later abandoned and a separate location chosen nearby.
1963 - a scroll is presented to John F Kennedy during his state visit to Ireland, this scroll contained the 1336 peace treaty signed in Nenagh Castle.
1971 - First proposal of Nenagh Town Council for castle restoration
2006 - Minister for the Environment, Heritage and Local Government Dick Roche announces a €3 million Visitor Centre for Nenagh Castle. This scheme would involve the refurbishment of the castle and would incorporate two properties on Pearse Street to house an interpretative centre.
2012 - only the restoration of the keep and installation of four floors is completed due to funding constraints.