In north Westmeath, the historic site of Fore Abbey and its Seven Wonders is certainly worth a visit as are the gardens of nearby Tullynally Castle. This area of the county is particularly pretty with picturesque country scenes and easy access to lakes. Lakes Lene, Owel and Derrvaragh the latter of which is associated with the famous Irish legend The Children of Lir are all situated north of Mullingar.
Further information on attractions in North Westmeath can be found on http://www.discoverireland.ie/westmeath