Doyle laid the foundation stone in 1892 and needed forty thousand pounds to finish the job - a fortune for a frontier diocese. Then the times turned against him. The economic depression of the 1890s and the Australian banking crisis of 1893 shuttered banks and froze the project for years. Work resumed in 1904, only for a fire in 1905 to destroy the neighbouring convent and school and set everything back again. Doyle simply refused to stop. He borrowed money, with the Presentation Sisters standing as his guarantors, and travelled his diocese five days a week, collecting donations and selling whatever he could to feed the building fund. The cathedral went up as the cash trickled in, course by course, until it was largely complete and dedicated in 1907 by Cardinal Francis Moran.

To design his cathedral, Doyle commissioned Herbert Wardell, son of William Wilkinson Wardell, one of the great architects of Catholic Australia. The elder Wardell had shaped St Patrick's Cathedral in Melbourne and the rebuilt St Mary's in Sydney, and the son carried that Gothic Revival vocabulary north to Lismore. The result is a pointed-arch, soaring-clerestory church that would not look out of place in a European cathedral city, transplanted to a subtropical river town. The original drawings included a great spire that was never built - the tower rises only to its base - so the cathedral wears a kind of dignified incompleteness, a reminder that ambition and budget rarely finish in step.

In 1908 Doyle sailed to his native Ireland and ordered twelve bells from a Dublin foundry, a personal gift to the diocese. He never heard them ring. After returning to Australia he died suddenly of a brain haemorrhage at his Lismore home in June 1909, and was buried in the cathedral he had willed into being. The bells arrived after his death to find no tower to hang in, and sat waiting on the docks. Over the next two years the bell tower was finished and the bells installed by public subscription, consecrated in 1911 - the largest of them weighing more than two tonnes. A successor noted that the community had raised slightly more than the work cost, leaving a small surplus to beautify the grounds. Doyle's bells finally rang out over the city he had chosen against all advice.

The cathedral's name carries a small geographical riddle. St Carthage's was named after the cathedral of the same name in Lismore, County Waterford, in Ireland - yet the Australian Lismore was not named after that Irish city at all. The town took its name instead from the tiny island of Lismore in the Inner Hebrides of Scotland. So the building honours an Irish saint and an Irish cathedral while standing in a city named for a Scottish island, a tidy knot of the migrant geography that settled this corner of New South Wales. Later bishops added their own touches: a pipe organ in 1912, an Australian-marble altar in 1919, and a mosaic shrine to St Patrick in 1937.

St Carthage's sits on a hill, which is usually what saves a building in Lismore. In the catastrophic flood of February 2022, when the Wilsons River reached its highest level on record, even the hill was not enough. Water entered the cathedral, lifting and shifting its heavy timber pews, though the sanctuary itself was spared. A second major flood weeks later, and the slow grind of cleanup that followed, kept the cathedral closed for months. It is a fitting modern chapter for a building defined by perseverance. The bishop who raised it brick by brick through depression, fire and his own death would likely have recognised the response of the parish that scrubbed out the mud and reopened the doors - the same refusal to be beaten that put the stones there in the first place.