Dublin Castle built
1204 CE.
Shown on the map at 53.343°, -6.267°.
Dublin Castle (Irish: Caisleán Bhaile Átha Cliath) is a major Irish government complex, conference centre, and tourist attraction. It is located off Dame Street in central Dublin. Originally a motte-and-bailey castle chosen for its position at the highest point of central Dublin, it was mostly rebuilt, from the late 17th century onward, as a Georgian palace. Many of the current buildings date from the 18th century, though a castle has stood on the site since the days of King John, the first Lord of Ireland. The Castle served as the seat of English, then later British, government of Ireland under the Lordship of Ireland (1171–1541), the Kingdom of Ireland (1541–1800), and the United Kingdom of Great Britain and Ireland (1801–1922). Until 1922 it was the seat of the British government's administration in Ireland. After the signing of the Anglo-Irish Treaty in December 1921, the complex was ceremonially handed over to the newly formed Provisional Government led by Michael Collins. It now hosts the inauguration of each President of Ireland and various State receptions. The castle was built by the dark pool (Dubh Linn in Irish) which gave Dublin its name.
Text from the Wikipedia article Dublin Castle, licensed CC BY-SA 4.0.