That the building evolved, layer by layer, through at least four distinct phases of alteration into something that a contemporary observer could describe as a coherent and agreeable composition is, as George Newenham Wright noted in 1831, quite singular. The result, an Ionic colonnade fronting a pedimented centre block with flanking wings, gives little outward sign of the piecemeal negotiation behind it.

Nathaniel Clements erected the original structure in 1751, a plain brick building on the walk within the Phoenix Park then known as Newtown Park. Clements held the position of chief ranger and game-keeper of the royal parks in Ireland from that same year, succeeding Sir John Lewis Ligonier in the role, which gave him both the means and the situation to build there. In 1784 the government purchased the house from Clements to serve as a country seat for the Lord Lieutenant, the Crown's representative in Ireland, and it appears as such on John Taylor's 1816 map of Dublin. The subsequent alterations came in quick succession: Lord Hardwicke added the wings in 1802, one of which contained the main dining hall; the Duke of Richmond contributed a north portico in the Doric order in 1808, along with the gate lodges at the Dublin-facing entrance to the demesne; and Lord Whitworth later oversaw the addition of the Ionic colonnade to the south front, designed by the architect Francis Johnston, which re-faced the whole facade to give the building its present character. When King George IV visited Ireland in 1821 and stayed here rather than at Dublin Castle, it briefly became known as the Royal Lodge. The pleasure grounds at that time extended to one hundred and sixty-one acres and included two ponds stocked with trout, tench, carp, and pike, as well as gardens, orchards, and rides through plantations.

Áras an Uachtaráin sits within the Phoenix Park and is not open to casual drop-in visits, though guided tours of the house and grounds are offered free of charge on Saturdays, running from the Phoenix Park Visitor Centre. Numbers are limited and booking ahead is advisable. The south front, with Johnston's Ionic colonnade, is the elevation most often seen in photographs, but the gate lodges erected by Richmond's direction at the demesne entrance are also worth pausing at. The limes and elms noted by Wright as framing views towards the Wicklow and Dublin mountains still frame the approach on the south side.