County Offaly: See
Clonmacnoise is Offaly's top attraction, an extensive monastic complex on the Shannon riverbank.
Castles: Charleville Forest Castle in Tullamore is a Gothic building surrounded by ancient oaks.
Bogs and wetlands: Lough Boora west of Tullamore and Clara Bog are two examples. They've been scarred by peat extraction, but that has now ceased.
Shannon callows are lowlands along the river and its tributaries. Some is wetland, but most is farmland undefended against floods, so it's a distinct semi-wild habitat. A good example is the callows of the Little Brosna south of Banagher.