The Oak Park Triumphal Arch was designed and constructed in the 1830s by the renowned architect father-and-son partnership William Vitruvius Morrison and Richard Morrison, commissioned by Colonel Henry Bruen, who had purchased Oak Park House in 1775.

Although the arch once served as a formal entrance gateway to the estate, it no longer functions in that role today, as a public road now passes through the site. Even so, the structure remains architecturally significant. Triumphal arches are rare in Ireland, and Oak Park is regarded as one of the few examples ever constructed, lending it considerable historical and cultural value.

The arch was once inhabited by a gatekeeper, and the final person known to have lived there was a man named Peter. Local tradition holds that Peter was friendly with the Browne-Clayton family, who owned the Oak Park estate during the 1930s and 1940s. Peter had served in the British Army during the First World War, and on his return is said to have suffered from what would now be recognised as post-traumatic shock. As a result, he was unable to resume his former duties.

Peter spent the remainder of his life living within the two “legs” of the arch, both of which were fitted with doors and internal living space. He died shortly before the outbreak of the Second World War, bringing an end to the arch’s residential use.

In December 2004, a photographer visited the site after it was recommended to him by a local historian. While examining the structure, he paced out the external measurements of the arch’s legs before climbing onto a nearby wall to look through a window, where he noticed the remains of a fireplace inside. Passing through the arch, he turned back to further inspect the interior — and it was then that he experienced something unexpected.

According to his account, he saw the figure of a man standing between the legs of the arch. The figure appeared semi-transparent, and while no facial features, clothing, or hair could be clearly made out, its height and proportions were unmistakably human. Almost immediately, the photographer felt an intense chill, accompanied by a sudden and overwhelming sense of sorrow. He reportedly spoke aloud, saying, “You poor soul. God help you.”

The apparition remained visible for approximately 15 to 20 seconds before fading from view. Shaken, the photographer later contacted the historian who had suggested the site and relayed the experience. The historian stated that this was the first reported sighting of a human-shaped apparition at the arch. However, he also noted that older local stories spoke of a mysterious light seen moving between the legs of the arch at dusk or in the early evening – a phenomenon long discussed but never conclusively explained.