Helen's Tower stands on the top of a wooded hill between Bangor and Newtownards, County Down, Northern Ireland.

A similar but higher landmark, Scrabo Tower, built by the Londonderrys, stands on the next hill to the south.

Frederick Temple Blackwood became the 5th Lord Dufferin and Claneboye and inherited the estate at his father's untimely death in 1841, while still a minor.

As that year was the worst of the Great Famine, the work might in part have been motivated by the desire to help people affected by offering employment.

The building's outside was complete by November 1850 when it was formally named Helen's Tower in honour of Dufferin's mother, who was 43 at the time.

In 1975 Helen's Tower was listed as a Grade A historic building[4] After a period of neglect, it was restored in the 1980s and can now be rented as holiday accommodation from the Irish Landmark Trust.

The base, which contains the ground floor, has battered outer surfaces that pass without break into the vertical walls of the tower's main body.

The base and the main body are square in plan and comprise a round stair tower that projects from the northeastern corner.

They have steep concave conical roofs, covered with slate at the bottom, capped with lead at the top, and crowned with ball finials.

The chamber has a slate saddle roof with an east-west trending ridge that ends in crow-stepped gables, which form the highest points of the turret and indeed the whole tower.

Small gabled wall dormer windows break the mids of the turret's eaves, one on the northern and one on the southern side.

A similar device appears on the gable of Helen's Bay railway station (1863) where however the two Ds are interlaced to form a proper monogram rather than a cypher.

The description of Helen's Tower on the historic building list says the cypher is short for Dufferin and Ava,[10] interpreting the second D as a lowercase A.

The walls of the tower are built of a dark massive stone, called "blackstone", laid in rubble courses.

This stone seems to be mostly the local Ordovician-Silurian greywacke that outcrops on the hill's slopes around the tower with perhaps some dolerite (also called basalt).

[15][16] The sitting-room on the second floor has a coffered ceiling, the panels of which are filled with painted roundels formed by circular inscriptions enclosing coronets or crests.

Would my granite girth were strong As either love, to last as long I should wear my crown entire To and thro’ the Doomsday fire, And be found of angel eyes In earth’s recurring Paradise.

Her sister Caroline Norton also was a successful writer, and their grandfather was Richard Brinsley Sheridan (1751–1816), playwright, poet and owner of London's Drury Lane theatre.