File:Belfast City - Crumlin Road Gaol (5702354450).jpg

HMP Belfast, also known as Crumlin Road Gaol, is a former prison situated in north Belfast, Northern Ireland. It is the only Victorian era prison remaining in Northern Ireland and has been derelict since 1996. It is popularly known as the Crum.

The Northern Ireland Environment Agency has given it a grade A listed building status because of its architectural and historical significance. The Crumlin Road Courthouse, also derelict, stands opposite the Gaol. A tunnel under the main road connects the two buildings and was used to transport the prisoners to the courthouse. During the history of the prison between 1846 and 31 March 1996, when it was closed, an estimated 25,000 prisoners were held here.

Designed by Sir Charles Lanyon, the prison was built between 1843 and 1845 and cost £60,000. Built as a replacement for the County Gaol on Antrim Street in Carrickfergus, and known as the County Gaol for Antrim, it was constructed of black balsalt rock on ten acres at the bottom of the Crumlin Road. Partly based on HM Prison Pentonville, it was one of the most advanced prisons of its day. Built within a five-sided wall, the four wings are up to four storeys in height and fan off from the central area which was known as The Circle. The prison was originally built to hold between 500 and 550 prisoners in cells that measured 12 x 7 feet. It was the first prison in Ireland to be built according to "The Separate System", intended to separate prisoners from each other with no communication between them. Later, especially in the early 1970s, as many as three prisoners were placed in each cell.

The first 106 inmates, who were forced to walk from Carrickfergus Prison in chains, arrived in 1846. These inmates, who were men, women and children, completed the changeover of the two prisons. Children from impoverished working-class families were often imprisoned at the gaol in the early years for offences such as stealing food or clothing. Women inmates were kept in the prison block house until the early 1900s. Ten year old Patrick Magee, who had been sentenced to three months in prison hanged himself in his cell in 1858.