Glashare Castle is a tower-house standing in the old civil parish of Glashare.

Prior to the middle of the sixteenth century, the castle was held for the Earls of Kildare.

Following the fall of the house of Kildare, the castle passed into Butler hands, and was held for them by the Graces of Foulkscourt.

The Church of Glashare was located in the field to the north of the castle, still called the Church Field, although no trace of the church itself survives. A small graveyard is still to be seen beside this field, the oldest inscribed memorial in which dates to the middle of the eighteenth century.

The castle appears to have been vacated, at least temporarily, in the seventeenth century, and this was lamented by a Gaelic poet at the time. In particular, the poet mentions the hopitality enjoyed by rich and poor alike in the castle in its heyday.

The author was Tuileagna Ó Maoil Chonaire. He was a poet and historian who lived in Bayswell around the year 1600. His daughter was married to a Grace from Moneynamuck.

These are the first two verses:

A mhná, guileam tre Ghlais Áir / is tugam ar dtreas 'na dhiaidh; / combáidh ghuil is déanta dhúin, / 's créachta an dúin gan luibh gan liaigh.

Och, ochán! adhbha na sluagh / 'na bhfaghbhadh gach bochtán biadh; / níor bh'fhiú cách a cur ar gcúl; / ag gul fán dún go bráth biam.