The story of Altinaghree's collapse is, at its heart, a story about a son who would not be the man his father wanted. William Ogilby built the castle. He had wealth, two sons, and a clear vision of dynasty. His younger son James Douglas Ogilby fell in love with Mary Jane Jamieson, a factory seamstress, and was forbidden to marry her because she was a Catholic. James eloped with her in 1884 and the family did the only thing Victorian Protestant Tyrone could think of to do: they cut him off. He sailed for Australia. In 1885 he was appointed to the Australian Museum, where he became one of the most prolific ichthyologists of his era, naming hundreds of species of fish across the South Pacific. By the time he died in 1925, more than seventy fish carried his name in their Latin binomials. Few of them have ever swum within ten thousand miles of Tyrone.

The estate passed instead to William's eldest son, Claude William Leslie Ogilby. Claude inherited the castle and the lands and the expectation of being the next country gentleman of Liscloon. He could not do it. He drank. He drank in the way that Victorian wealth made possible and Victorian respectability tried to hide. By 1875, at the age of forty-three, his kidneys had given out. Chronic alcoholism, the death certificate said, in language slightly more elaborate than that. He died ten years before the castle was abandoned and his death rendered the abandonment inevitable. The estate could not be made to pay; the heir was gone before he could even try. Bankruptcy followed, and the great banquet room hosted its last dinner sometime before the new decade began.

Altinaghree sits on private farmland a few miles outside Donemana, south of Derry in County Tyrone. The cut stone walls still rise to roughly their full height; the empty windows still hold their carved arches; ivy has done what ivy does. The small row of workmen's houses to the southeast, the Liscloon Cottages, were absorbed back into the working life of the farm and now shelter tools and feed. There is no admission, no caretaker, no plaque. You can photograph the building from the road to Claudy if you know where to look between the hedges. The B49 runs past as it always has. The Sperrin foothills rise to the south. The story this stone tells, of an Ulster Protestant patriarch who lost one son to love and the other to drink and saw the family's whole architectural ambition flicker out within a generation, is a story repeated in different keys across rural Ireland in the late nineteenth century. The castles fell because the world that had paid for them was passing. Altinaghree fell faster than most, because the wrong things happened to the wrong people at the wrong time.

There is one survival from all this, and it lives in the catalogues of marine biology rather than in the stones of Tyrone. James Douglas Ogilby, the son who would not give up the seamstress, became one of the most respected ichthyologists in Australia. The Australian Museum still holds parts of his collection. His descriptive papers on the fishes of New South Wales and Queensland are still cited. Several species, including the Brisbane River blue eye, were first described by him. He is not the kind of figure who shows up in tourist brochures. But it is fair to say that William Ogilby's castle, the cut-stone monument he built to perpetuate his line, lies in ruin while the name he tried to deny his son is alive in Latin in scientific journals on three continents. There are worse legacies than that, and Altinaghree's silent walls cannot really argue with the result.