The building looks, at first glance, like a fairly undistinguished early twentieth-century structure, all flat concrete roof and rendered piers. But beneath that later skin is something older and stranger: a Napoleonic-era watchtower, originally completed by 1805 and designed to scan the Atlantic for French warships.

The tower was one of more than eighty signal stations constructed by the British Board of Ordnance in the first decade of the nineteenth century, forming a continuous coastal chain from Dublin Bay clockwise around the entire Irish coastline as far as Malin Head in County Donegal. Each station communicated with its neighbours using a naval signal post; the Bray Head tower could, in theory, pass a warning northeast to Great Blasket Island, about 24.5 kilometres away, or southeast to Bolus Head, roughly 11.5 kilometres distant. The whole system was stood down by the mid-1810s once the threat of a Napoleonic invasion faded. The original tower was a two-storey rubble stone structure, and in its earlier form it featured a machicolation, which is a projecting parapet opening through which defenders could drop objects on attackers, over the first-floor doorway, and bartizans, small corner turrets corbelled out from the wall, on its northeast elevation. A photograph from the Lawrence Collection, taken around 1890, still shows these features, along with the ghost of a since-demolished single-storey building pressed against the same wall. When the Royal Navy returned to the site during the First World War, reusing it as a Naval War Signal Station, they stripped away those earlier details and refurbished the tower extensively, adding the flat reinforced concrete roof dated to around 1915, new ground-floor entrances, concrete porches, and a cement render that now covers everything. The base of what was probably a radio mast still sits to the southwest of the tower on its original concrete footing. Beneath and around all of this, the site carries still older layers: a possible coastal promontory fort sits at the very tip of Bray Head to the southwest, and another lies roughly 1.38 kilometres to the south at Beenaniller Head.

The enclosure walls that ring the tower survive along most of their length, and a cement pathway still runs from the northeast gateway to the tower door. Approximately 115 metres to the southwest, a large numeral laid out on the ground marks the site as 'Eire Sign 35', one of the coastal neutrality markers placed during the Second World War to identify Irish territory to overflying aircraft, adding yet another military footnote to a ridge that has, by this point, accumulated rather a lot of them.