The Magazine Fort is not especially large, covering just over two acres, but its history is compressed in a way that rewards close attention.

The fort was preceded by Phoenix House, a building demolished in 1734 to clear the ground for what would become the principal distribution centre for powder and munitions serving the Dublin barracks. Construction was completed around 1738, and an 1818 description records a square fort with demi-bastions at each angle, a dry ditch, and a drawbridge on the east side, armed with ten twenty-four-pound cannon. Demi-bastions are projecting angular structures built into the corners of a fortification, designed to eliminate blind spots and allow defenders to cover the walls on either side. The fort was modified around 1760, and then again in 1801 when a triangular range of brick buildings was added in front of the entrance, partly to billet troops who had previously been drawn from the nearby village of Chapelizod. Dean Swift, who lived from 1667 to 1745, left his own commentary on the whole enterprise: "Behold a proof of Irish sense / here Irish wit is seen, / when nothings left that's worth defence / they build a magazine." The verse was satirical, aimed at the perceived absurdity of a large fortification in a place with little left to protect. The fort continued in active use until the mid-twentieth century, outlasting Swift's scepticism by some considerable margin. On Easter Monday 1916, a small group of Irish Volunteers raided it successfully, and the signal given at that moment marked the beginning of the Easter Rising. The fort was raided again in 1939, when a substantial quantity of guns and munitions was taken, though these were subsequently recovered.

The fort sits within Phoenix Park, which is freely accessible, and the exterior of the structure can be viewed from the road that runs along the park's southern boundary. The triangular brick outworks added in 1801 are visible from outside and give a sense of how the entrance was layered with successive defensive additions over the decades. The dry moat, a ditch without water designed to impede attackers rather than carry drainage, is part of the original design and remains a legible feature of the site. The park itself is large enough that the fort is easily missed by visitors who stick to the central areas near the zoo or the main avenue, which is, in its own way, fitting for a place that history has repeatedly treated as an afterthought.