At the foot of the Dublin Mountains, just off a byroad leading to Castlefield Manor housing estate, stands Knocklyon Castle, a medieval tower house with a long and varied history.

Where Rathgar Road meets Orwell Road today, there once stood a formidable castle that played a witness to centuries of Irish history.

On the south side of Malahide estuary stands Seatown Castle, a modest medieval tower house that has been quietly weathering the centuries since at least the 1650s.

In the low-lying grounds of what is now Corkagh Demesne County Council Park, at the foot of the Dublin Mountains, once stood a fortified site that tells a story of Ireland's layered past.

East of the River Dodder in Dublin's flat terrain sits what remains of Simmonscourt Castle, a medieval stronghold that once dominated this corner of south Dublin.

In the countryside of County Dublin, the grounds at Cheeverstown hold subtle clues to a fortified past that has all but vanished from view.

Standing on the south side of Castle Street beside the Roman Catholic Church of the Assumption, Dalkey Castle cuts an imposing figure in this coastal Dublin suburb.

In the village of Clontarf, just outside Dublin, once stood a formidable defensive structure that has now vanished from the landscape.

On the south bank of the River Tolka in Pelletstown, County Dublin, a modest kidney-shaped mound marks the spot where a castle once stood.

At the southeast corner where Monkstown Avenue meets Mounttown Road Upper, a medieval gatehouse stands guard over what was once a fortified complex belonging to the Cistercian monks of St Mary's Abbey.

In the heart of Terenure, where a modern college now stands, lies a site with centuries of hidden history.

Dundrum Castle stands on an east-facing ridge south-southwest of Dundrum village, commanding views over the Slang River below.

Looking out over Dublin Bay from its elevated position in Clontarf, this castle site has witnessed nearly nine centuries of Irish history.

Where St Mary Magdalen's Convent now stands off Brookvale Road in Donnybrook West, there once rose an Elizabethan mansion with a rather grand history.

Where a modern business park now stands in south Dublin city, there once stood Donore Castle, a medieval stronghold that has completely vanished from the landscape.