The land was won in the seventeenth century, when the English Crown handed Westmeath estates to families who had been useful to Cromwell. The Handcocks came from Devon. By 1812 William Handcock had become the 1st Baron Castlemaine - a peerage promised to him in exchange for his vote in favor of the Act of Union. He had originally opposed it, but the title changed his mind. In 1814, on the lands his ancestors had purchased in 1684, he built his gothic-revival castle. Samuel Lewis's 1837 Topographical Dictionary of Ireland called it "a handsome castellated mansion, beautifully situated in an extensive demesne, on one side of which is a small lake." By the 1880s the barony comprised 11,444 acres. The Castlemaines were prominent at Lough Ree Yacht Club, and in 1920 Major G.S. Handcock chaired the committee that designed the Shannon One-Design dinghy, still sailed today.

On 20 June 1921, Major-General Thomas Stanton Lambert was killed near Moydrum by an IRA flying column that had hoped to take him alive and exchange him for the captured General Sean Mac Eoin. In reprisal, the Black and Tans burned several farmsteads in south Westmeath. The local IRA decided on a counter-reprisal. They picked the castle for its symbolism: this was the seat of a member of the House of Lords, the visible center of British landlord power in the area. On the night of 3 July, they knocked at the door. Lord Castlemaine was abroad. His wife, his daughter, and several servants were home. The IRA gave them a short time to gather what valuables they could carry, ordered them out, and set the castle alight. By morning it was a roofless shell. The family never came back.

Sixty-three years later, Anton Corbijn brought U2 to the ruin to shoot a sleeve. He used the same vantage point, the same polarizing filter, and the same infrared film as a 1980 photograph by Simon Marsden, from a book called In Ruins: The Once Great Houses of Ireland. The composition was nearly identical, with only the band members added; U2 eventually had to pay Marsden compensation. The sepia tone came in post-production. The infrared chemistry made the late summer leaves shimmer like snow and the blue Westmeath sky read as deep black behind the broken stone. The album, U2's fourth, opens with "A Sort of Homecoming." The cover is exactly that - a homecoming to a country in which the homes had been emptied. After release, fans started showing up at Moydrum. Locals were unprepared. Some of the ivy on the walls today grew in over years of pilgrims taking selfies in front of a building most of them could not have named.

After the burning, the Castlemaine lands were broken up by the Irish Land Commission, divided, and sold on to local farmers. The barony of 11,444 acres became hundreds of smaller holdings, the great estate dissolved into the working countryside of independent Ireland. The castle itself stayed in private hands as a roofless ruin, slowly disappearing into the ivy. Today it remains on private land east of Athlone; the only way most people see it is the way Corbijn shot it, framed by trees, in a black-and-white photograph older than they are. Nearby Mount Temple - where Elizabeth Temple rode up the motte - and the village of Baylin are part of the same parish. They all share the long Westmeath story of conquest, settlement, and the moment when the conquered, finally, took their country back.