Survey Data

Reg No




Categories of Special Interest

Architectural, Historical

Previous Name

Glenhead Signal Tower

Original Use

Signal tower


1800 - 1810


151933, 386944

Date Recorded


Date Updated



Freestanding two-storey former signal tower on square-plan, built c. 1805, having machicolations to the north-east and south-east corners and with central machicolation/bartizan to the west elevation at parapet level. Now out of use and derelict. Flat roof, now collapsed, originally hidden behind raised parapet having cut stone coping over. Parapet damaged and partially collapsed to the north-west corner. Constructed of rubble and roughly squared rubble stone masonry with flush roughly squared quoins to the corners. Slightly battered/splayed to base. Evidence of lime roughcast render still surviving in places; pointed walls to the east. Ashlar supports/corbels to machicolations. Square-headed window openings having cut stone sills, cut stone surrounds, and with cut stone block-and-start surrounds with keystone detail at first floor level and cut stone surrounds with keystone detail to ground floor openings. Rubble stone relieving arches to ground floor window openings. Probable square-headed former doorway to the west elevation at first floor level having cut stone block-and-start surround with keystone detail. Located on cliff top location overlooking the Atlantic Ocean to the west and north-west, and Skelpoonagh Bay and Glen Bay to the south. Located to the north-west of Gleann Cholm Cille/Glencolumbkille.


This notable former Napoleonic-era signal tower occupies a dramatic coastal location, and is a prominent local landmark to the north-west of Gleann Cholm Cille/Glencolumbkille. This structure is one of upwards of eighty such buildings that were constructed along the west, south, south-east and north-west coastlines of Ireland by British authorities between 1804 and 1806 in reaction to the various French invasion attempts in the 1790s, particularly the 1798 French landing at Killala in County Mayo. Signal towers were generally built to the same plan, although some slight regional variations are found. They worked on a signalling system using ball and flag methods, where various messages could be transmitted from station to station, quickly raising the alarm in case of the siting of enemy vessels and fleets etc. A c. fifty foot mast was positioned on the seaward side of the signal tower where the flags and balls would be hoisted so that the next signal tower could see the message and pass it on to the adjacent one and so forth. In order to cut construction costs etc., signal towers are, as a rule, located on high ground with a clear line of sight over the sea and to the neighbouring towers to either side (in this case Malin Beg (see 40808901) to the south and Dawross Head to the north-east). Therefore, the presence of a signal tower guarantees spectacular views and situations, as is the case here at Glen Head. Following The Royal Navy’s (under Nelson) victory over the French and Spanish fleets at the Battle of Trafalgar in 1805, the threat of invasion diminished substantially, and by 1809 the decision was made to abandon the signal towers that are dotted along the Irish coastline. These structures now act as tangible historical documents of this era in Irish history, and are appealing landmarks of some picturesque value along the Irish coastline. This example at Glen Head is notable in that it survives in particularly good condition, and it is one of the few buildings of its type that still retains the high quality cut stone surrounds to the openings (these have been robbed from other sites). The machicolation to the centre of the west elevation was sited to defend the main entrance below, which was accessed via a retractable ladder. Signal towers cost between €600 to £900 each to construct. The construction of this signal station at Glen Head and a number of others in Donegal was overseen by Major-General Sir Charles Ross, and the engineer involved may have been a Sir William Smith, who was responsible for a number of the Donegal signal towers. Construction begun here in 1804 and was completed by September 1806.