Portlaoise Prison is Ireland's only high security prison. It is located in Portlaoise, County Laois. It should not be confused with the Midlands Prison, which is a newer, medium security prison situated directly beside it.The prison was built in the 1830s, making it one of the oldest still operating today in the Irish prison system. It is particularly notable as the prison in which people convicted of membership of the Provisional Irish Republican Army (IRA) and other illegal paramilitary organisations are usually detained.Today the majority of the inmates are Ireland's most dangerous criminals, members of dangerous drug gangs, and criminals serving life sentences for serious crime. A number of Irish Republican prisoners are still in the old E Block. Anyone charged under Section 30 of the Offences Against the State Act must be sent to the prison because of its unique security measures.SecurityThe prison has a capacity for 399 prisoners, but because of the security sensitive nature of its inmates, it operates below this capacity and its daily average number of resident inmates was only 119 in 2009. A large number of well armed Irish Defence Forces soldiers guard the prison 24 hours a day, making it one of the most secure prisons in Europe.The security features include an army detachment consisting of approximate Company strength, armed with assault rifles and anti-aircraft machine guns, who guard the prison complex. An air exclusion zone operates over the entire complex. The perimeter consists of high walls, cameras, and sensors and anti-tank measures (Czech hedgehog).