Birr

A Georgian estate town around Birr Castle, where in 1845 the third Earl of Rosse built the Leviathan of Parsonstown — a 72-inch reflecting telescope that was the largest in the world for over seventy years, and through which the spiral structure of galaxies was first seen.

St Brendan of Birr founded a monastery here, which produced the MacRegol Gospels, named after an abbot of around 800 and now in the Bodleian Library. At the Synod of Birr in 697 the Cáin Adomnáin, the Law of the Innocents protecting non-combatants, was proclaimed. In Gaelic Ireland Birr was in the O'Carrolls' country of Éile, and their castle stood where Birr Castle is now.

The town as it stands dates from the 1620s, a market and garrison town. In the 19th century it was the scene of the Crotty Schism, one of the few splits in the Catholic Church in Ireland, and Crotty's Church still stands on Castle Street. From 1881 Birr Barracks was the depot of the Leinster Regiment; it was burned in the Civil War in 1922, and only its outer wall remains.

Drawn from the History section of the Wikipedia article on Birr ↗, rewritten here and adding nothing it does not say; licensed CC BY-SA 4.0.

• Seir Kieran · round tower · 8 km
• Kinnitty Cross · high cross · 14 km
• Birr Castle · castle · under 1 km
• Leap Castle · castle · 10 km
• Lackeen Castle · castle · 11 km
• Kinnitty Castle · castle · 14 km
• Redwood Castle · castle · 15 km

Straight-line distances from the town centre, from each site's documented coordinates.

• Portumna Workhouse · The best-preserved of the 163 workhouses: dormitories, the 'idiots' ward', the separate yard where families were split by rule the day they entered.
• Slieve Bloom — where Fionn was reared · Clann Morna had killed his father, so the boy Fionn was taken into these mountains and raised in hiding by two women — the poet Bodhmall and the warrior Liath Luachra. The range takes its name from Bladh, and it straddles Laois and Offaly.

All of these are pinned on the Hidden Ireland map.