Mud Island's monarchy was a real institution. The islanders elected their king, often but not always from the extended MacDonnell family. Two of the more famous ones were Art Granger and 'Grid Iron' MacDonnell. The Irish Builder described the place sourly in 1870 as a low marsh that had been 'under the influence of the sea' until embankments cut it off. The 1911 Irish Times ran a series of interviews with descendants of the original families, recording memories of smugglers, highwaymen, and robbers who had used Mud Island as a base for raids on the Drogheda Road. Newspaper crime reports from earlier decades confirm the substance of the stories: this was a hard place to police, run by its own internal rules, deliberately ignored by city authorities who preferred not to look. King's Avenue, just off Ballybough Road, still carries the title in its street name. Land reclamation in the nineteenth century eventually folded the island back into the mainland and the kingdom dissolved.

Ballybough Bridge - now Luke Kelly Bridge, renamed in 1985 for the Dubliners singer who lived nearby - has stood in various forms since 1313, when the mayor John Le Decer built the first wooden crossing of the Tolka here. Floods quickly destroyed it; rebuilding continued through the centuries. Some historians believe the Battle of Clontarf in 1014, in which the High King Brian Boru defeated a Norse-Leinster alliance, was fought in the immediate vicinity of the bridge, near a feature known as the Fishing Weir. In 1534 it was the site of another bloody engagement: Silken Thomas's rebellion against Henry VIII brought his forces here against a Crown garrison, and the resulting fight left, in the words of one chronicler, 'great slaughter of Englishmen' at the bridge and in nearby Clontarf. The current concrete bridge dates from 1937, replacing the medieval stone structure that had survived in various forms for over six hundred years.

Ballybough Cemetery, on Fairview Strand, was the first Jewish burial ground in Ireland. In 1718, Captain Chichester Phillips of Drumcondra Castle signed a forty-year lease with four men whose names record the history of Dublin's small Sephardic community: Alexander Felix, Jacob de Porto, David Machado de Sequeira, and Abraham Meirs. The Jewish population of Dublin at the time was concentrated in Annadale, north of the Tolka. For 182 years - through penal restrictions, brief emancipations, the famine, and the early years of mass migration from the Russian Empire - Ballybough remained the only Jewish cemetery in the city. A new ground opened at Dolphin's Barn in 1900. The last burial at Ballybough took place in 1908. The cemetery is still there, a small walled enclosure on a busy street, with stones inscribed in Hebrew and English, a reminder that Dublin had a tiny Jewish presence two centuries before most Dubliners realised it.

Like much of north inner-city Dublin, Ballybough fought through the Easter Rising and the War of Independence. The Irish Citizen Army seized a factory at Annesley Bridge in 1916 and held it for a day. The 2nd Battalion of the IRA engaged British forces at Ballybough Bridge during the War of Independence. The RIC barracks on Fairview Strand was attacked. One of the conflict's final incidents played out on Bayview Avenue, in an IRA ambush of British soldiers conducting a raid. The single most notorious atrocity of the war happened a few hundred metres north, in Croke Park - Bloody Sunday, 21 November 1920, when Auxiliaries opened fire on a crowd attending a Gaelic football match, killing fourteen civilians including the Tipperary player Michael Hogan. In 2020, the bridge that links Jones's Road to Russell Street, which used to be called Clonliffe Bridge, was renamed Bloody Sunday Bridge in their memory. The Bombing of Dublin in May 1941 - a German attack widely believed to have been navigational error - damaged parts of Ballybough, killing residents and leaving hundreds displaced.

Two voices of twentieth-century Dublin grew up in Ballybough's streets. Brendan Behan, the playwright and memoirist of Borstal Boy and The Quare Fellow, was born on Russell Street and learned the city in its pubs and lock-ups. He was a student at O'Connell Schools on North Richmond Street, founded in 1828 by Edmund Rice and the Christian Brothers. Luke Kelly, the rough-voiced lead singer of the Dubliners folk group, lived nearby and is remembered in the bridge that now bears his name. The stonemason Edward Smyth, whose sculptural figures decorate the Custom House, the Four Courts, the Bank of Ireland on College Green, and the Chapel Royal in Dublin Castle, lived in Ballybough during a working life that helped give Georgian Dublin its sculpted face. Edmund Rice himself, founder of the Irish Christian Brothers, spent time in the area. So did Matt Talbot, the labourer and reformed alcoholic whose grave in Glasnevin still draws pilgrims. Ballybough has produced and harboured an unusually high proportion of the people Dubliners now name their bridges after.