Another explanation is that it is derived from a stone cross that marked the boundary of lands held by the Danish Harold family of Rathfarnham in early medieval times, reputedly located at what is now the five-road Kenilworth junction on Harold's Cross Road.
In any event, the area has been recorded since at least the 1100s.
At one side of Harold's Cross is Mount Jerome Cemetery, as mentioned in Joyce's Ulysses, originally a residence of a family named Shaw. It is considered Dublin's most gothic cemetery and there lie such lumunaries as Thomas Davis, George Russell, and Oscar Wilde's father, William Wilde, in addition to former members of the Guinness family, deceased members of the Royal Irish Constabulary, and the remains of the French Huguenots once buried in the St. Stephen's Green Cemetery. Another famous grave is that of William Rowan Hamilton, the famous Irish mathematician. Famous Irish playwright, John Millington Synge. The cemetery was operated from 1837 to 1984 by a private company and now belongs to the Massey family.
The suburb is also home to Dublin's first hospice, Our Lady's Hospice, Harold's Cross (the organisation also runs a hospice at Blackrock). This palliative care facility was founded in 1879 in a house called Our Lady's Mount (formerly Greenmount), which was previously the Mother House of the Religious Sisters of Charity, by that order. A new Hospice building was commenced in 1886, and many more buildings have followed.
Saint Clare's Convent and Primary School.
Mount Argus Church and Monastary, which was the official home of Saint Charles of Mount Argus who was a well known Passionist priest in 19th century Ireland. It also has long established links with the An Garda Siochana as being officially the church of the Dublin Metropolitan Police.
The closed Church of Ireland parish in Harold's Cross has been leased to the Orthodox Christian community as Ss Peter and Paul Russian Orthodox Church. A rather large congregation made up of Orthodox residents in Ireland (mostly from the former USSR, Eastern Slovakia and Poland)) along with native (mostly convert) Irish Orthodox attend services here. Services are conducted both in Church Slavonic and English with a smattering of Gaelic.
Irish nationalist rebel leader Robert Emmet was captured near Harold's Cross. He led an abortive rebellion against British rule in 1803 and was captured, tried and executed. There is a plaque on bridge of the grand canal between Harolds Road and Clanbrassils street commemorating him.
The father of Pádraig Pearse, James was a stonemason for Mount Argus Church. The Rebels who had a training ground in nearby Kimmage are said to have paid a visit to Mount Argus Church to pray just before they meet there faith on the day of the 1916 Easter Rising.
The O'Connors Jewellers on Harolds Cross Road, is noted for being one of the two famous robberies by a notorious Dublin criminal Martin Cahill.