In its prime, the castle was inhabited by the Barrett family, who had control of the local area.

[4][5] While a date for this original construction is not confirmed, by 1468, the Barrett family purchased Coll's estate lands at Ballincollig, and improved and extended the castle site.

[6] The bawn (enclosure) and tower house are located on a limestone summit,[2] which has a line of sight over the low land of the Maglin Valley.

Beneath the castle there is a natural cavern which runs into the rock, and around it the remains of a moat.

[9] Three years later, Edmund got a decree of £100 against the Sheriff of County Cork, for refusing to execute a writ dispossessing Andrew Barrett and others who had seized the castle.

The family had borrowed money to pay for court fines and dowries, and obtained a mortgage on the castle and lands in 1618 from the Coppingers of Cork.

[9] Contemporary papers note that "William Barrett of Ballincollig in the County of Cork, gent,… in consideration of £240 paid by Edmond Coppinger Fitzrobert of Corke, gent, the said William Barrett granted to the said Edmond Coppinger, his heirs and assigns forever all that and those the castles, bawnes, towns, villages, hamlets, lands, tenements and hereditaments of and in Ballincolly…".

[14] There appears to be evidence of a hall in the middle, as one portion of the outer wall has the remains of a fireplace and chimney and a window of two lights.

It is suggested that the towers on the outer wall and the hall are of 15th century making and were probably built after the castle was sold to the Barretts by Robert Coll.

The second story has seats in the lambs of the loopholes, a drain from a garderobe (lavatory) and a small square cupboard in the wall over it.

[6] The upper floor and chief chamber seem to have had windows added on all sides in the middle of the 19th century.