Hillforts, promontory forts and Royal sites

Dún Aengus - Aran Islands (showing the chevaux-de-frise)
Hillforts are often sited in spectacular settings with commanding views over the countryside. The fort of Dún Aengus on Inis Mór, the largest of the Aran Islands which lie off the Galway coast, is one of the most dramatic of all. It is built at the edge of the steep cliffs on the sothern tip of the island.

Grainán of Aileach - west of Derry, one of the great forts with stone ramparts.

A perspective from The Grianán of Aileach

Summer has come, healthy and free,
Whence the brown wood is bent to the ground:
The slender nimble deer leap,
And the path of seals is smooth.

A sound of playful breezes in the tops
Of a black oakwood is Drum Dail,
The noble hornless herd runs,
To whom Cuan-wood is a shelter.

The sun smiles over every land -
A parting for me from the brood of cares:
Hounds bark, stags tryst,
Ravens flourish, summer has come!
(Old Irish poem)

Hill of Tara

Irish Teamhair na Rí, "Hill of the Kings"), located near the River Boyne.

(The most famous royal site in Ireland)

The mound of the hostages (Irish: Dumha na nGiall)
It's an ancient passage tomb located in County Meath.The mound was used for burials from the early Neolithic up to 1600 - 1700 BCE. There are an estimated 250 - 500 bodies buried in the mound, organised into layers under the passage. The dead were most often cremated, and their ashes and grave goods spread on the floor of the tomb. These grave goods include decorative pottery and urns, stone beads, and bone pins.

Eamhain Mhacha

Goddess Macha
She's a presumed goddess of ancient Ireland, associated with war, horses, sovereignty, and the sites of Armagh and Emain Macha in County Armagh, which are named after her. A number of figures called Macha appear in Irish mythology, legend and historical tradition, all believed to derive from the same deity.