Today there is no visible trace of any of it. The tower has gone, the batteries have gone, and what may remain are large, anonymous pieces of masonry tumbled onto the beach below, possibly shed from the structure as the cliff edge gave way over the decades. It is, in its own quiet way, a place defined entirely by absence.

The tower was one of a chain of coastal fortifications thrown up along the Dublin coastline in response to the threat of Napoleonic invasion. Construction began in 1804 under Colonel Benjamin Fisher of the Royal Engineers, and by December 1805 all the towers in the Dublin area had been armed and completed. Martello towers, for those unfamiliar with the type, are squat, thick-walled circular structures of considerable strength, designed to mount artillery on their roofs and resist cannon fire. The Dublin series south of the city was numbered 1 to 16, though only fourteen actual towers were built; at two locations, batteries were constructed without any accompanying tower. Shanganagh was designated Tower No. 4 in that sequence. A mid-nineteenth-century plan described by historian Paul Kerrigan recorded the tower as having semi-circular glacis, sloped defensive earthworks, to its east and west, with one battery positioned roughly 500 feet to the north and another 500 feet to the south. Taylor's map of 1816 still shows the tower and battery in situ. By the Ordnance Survey edition of 1863, the tower was marked as disused; by the time of the Cassini edition, it had ceased to appear on maps altogether. Kerrigan concluded that it was dismantled in the early years of the twentieth century, coastal erosion having already undermined the cliff on which it stood.

The site sits east of the disused railway line above the beach at Mahera Point, near Shanganagh. There is nothing to see in terms of standing structure, which is precisely what makes a visit oddly compelling for anyone interested in military archaeology or the quieter kinds of loss. The beach itself is accessible, and those willing to look carefully among the shoreline debris may encounter large masonry fragments that could plausibly be the tower's remains, though nothing has been formally identified. The 1837 Ordnance Survey six-inch map, which annotates the location simply as "Battery", offers a useful reference point for tracing the approximate position of what was once a significant piece of coastal infrastructure.