Cabra is a suburb on the northside of Dublin city in Ireland. It is approximately 2 kilometres (1.2 mi) northwest of the city centre, in the administrative area of Dublin City Council. It was commonly known as Cabragh until the early 20th century. Cabra is also a parish in the Fingal South West deanery of the Roman Catholic Archdiocese of Dublin.
Famous people from Cabra include singer-songwriter Eleanor McEvoy, world champion boxer Steve Collins, author and journalist Gene Kerrigan, actors Michael Gambon and Frank Grimes, actress and singer Angeline Ball, singer Dickie Rock and multi-time WWE world champion Sheamus (real name Stephen Farrelly).
Numerous footballers hail from Cabra, including Republic of Ireland international goalkeeper Wayne Henderson, and Eamonn Fagan and Liam Whelan, both from St. Attracta Road. Whelan was one of the Manchester United Busby Babes who died in the Munich air disaster of 1958, and Connaught Bridge was later renamed in his memory. The former Leeds United and Irish player and manager Johnny Giles also hails from the area. Roddy Collins, former manager of Bohemians, Shamrock Rovers and Maltese side Floriana, lived in Cabra before being appointed manager of Cork City.
The suburb's most infamous former resident was John Toler, 1st Earl of Norbury, otherwise known as the hanging judge, who lived at Cabragh House on the corner of the present day Fassaugh Avenue and Rathoath Road. One of the world's most famous mathematicians, William Rowan Hamilton, who freed algebra from the commutative postulate of multiplication (that the order or sequence of factors does not determine the result) was associated with the area. There is a plaque in his honour at Broom Bridge.
The Roman Catholic church of Christ the King was built during the years following the Eucumenical Congress of 1932. It seemed appropriate to employ John J. Robinson of Robinson and Keefe to design the new church, as he had been Architect for all the structures (Phoenix Park, Merrion Road, O'Connell bridge etc.) built for the Congress. The church which is cross shaped in plan was built in red brick with a huge statue of Christ integrated into the tower which is on the axis of the approach road. An Architect's perspective drawing of the church exists in the Irish Architectural Archive in Merrion Square. This church shares many features with St. Therese Mount Merrion which was built by the same Architect some 20 years later. Robinson is also famed as being Architect to Galway Cathedral.
Broom Bridge, also known as Brougham Bridge, is a small bridge along Broombridge Road which crosses the Royal Canal in Cabra. The bridge is named after William Broom, one of the directors of the Royal Canal company. Broom Bridge is the location where Sir William Rowan Hamilton, following a 'eureka experience', first wrote down the fundamental formula for quaternions on 16 October 1843, which is to this day commemorated by a stone plaque on the northwest corner of the underside of the bridge. The text on the plaque reads:
“Here as he walked by on the 16th of October 1843 Sir William Rowan Hamilton in a flash of genius discovered the fundamental formula for quaternion multiplication i² = j² = k² = ijk = −1 and cut it on a stone of this bridge.”
Given the historical importance of the mathematical contribution, mathematicians have been known to make a pilgrimage of sorts to the site.