Bog of Allen, group of peat bogs between the Liffey and the Shannon rivers in east-central Ireland in Counties Kildare, Offaly, Laoighis, and Westmeath. Some 370 square miles (958 square km) in area, it is developed extensively for fuel for power stations; the cutover land is used for grazing. The bogs are traversed by the Grand and Royal canals, the latter no longer in use. An early monastic site exists within the bog.